How to Solve Age Problems: Table Technique [CC] – Civil Service Review

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it says “in 4 years, Leah’s mother will be…” “will be” means is also equal, this age here is equal to “twice”, what does twice mean? that is, two times, “Leah’s age today”. Question, where is the box for Leah’s age today? That is this. Leah’s age now So, this one. It says that if I multiply this by 2
the result will be that. In traditional method, what will happen would be, this becomes X, this becomes X times 2 And, what I’m going to do right now will be I’m going to show you the traditional method and then I’m going to show you my way. Now that we have that, this is the traditional method X this will be X times 2. Problem states that “Leah will be 30 years old then” when it says “will be” it means it is in the future Leah then, in 4 years, will be 30 years old “how old is Leah’s mother now?” So, this is what is being asked. Okay? In that case, this means that we will go back to what will be the X. In order for to get a successful equation is you’re going to make Leah’s Mother the X, because she is the one being asked about. This is X. If Leah’s Mother is X, what happens to the equation is,
if you’re building using the traditional method, if this is X the X in 4 years this becomes X + 4. Now this X + 4,
as we’ve said before, X + 4 is equal to this times 2. So, we will divide this by 2 to return it. So, this becomes (X + 4) / 2. Then this (X + 4) / 2 when added by 4 will become 30. So, the equation becomes 30= [ (X + 4) / 2 ] + 4. Again, that is the traditional method. In traditional method… Again, I’m just gonna erase things to make room. Your equation becomes 30=[ (X + 4) / 2 ] + 4. Again, you can try solving that, okay, if you want. Another option would be to use trial and error. Now, the reason why I, basically, created this method. I could say that, maybe, because I don’t use this when I solve. But my problem is it’s so hard to teach people how to create the equation. So, I thought of a way to help you use trial and error,
and still get the correct answer without using Algebra. And I came up with this. I’m going to show you how to do it. Again, the basics are the same. You’re still going to create the table,
the tables look the same anyway. This is going to be 30 years old. Now, what we’re going to do differently is this. Instead of going through the process of creating the equation like this, we’re going to try to fill in all of the boxes The reason why I created this method is because it’s so hard to teach people how to create the equation. And so, the only way I thought of in order for you to, kind of, get a fighting chance, meaning to give the opportunity to answer the question, even though you don’t know how to use formula, and even though you don’t know how to use Algebra,
is this method. So, I want you to pay attention. If you need to watch this multiple times, go ahead and do it. I’m not expecting that once you’ve watch this, you’d understand already. That is the reason why I’m making this on YouTube. Before this was exclusive to TeamLyqa Online, but I’m opening this to everyone because I know this type of problem gives you a lot of problems when it comes to the exam. So what we will do here is we will fill the table of all the information we can extract from the table itself. We will reconstruct the table. We’re not going to use formula, we’re going to use common sense, a little bit of Math. Okay, this is how. If Leah is 30 years old in 4 years, it means in the future, she’s 30 years old in the future, how is she now? Of course, she’s younger now than in the future, right? All we have to do is
30 minus 4, this becomes 26, right? Because if she’s 30 years old in the future, 4 years in the future, she should be 26 now. Okay? Now that we have that, the question is how are we going to arrive to this circle that we’re trying to solve? Now, we’ve said that whatever this is, multiply it by 2,
this will be the answer. So all we have to do is 26 times 2, 26 times 2 is 52, we’ll put it here. Now if Leah’s Mother is 52 in 4 years, the question is how is she now? Same thing, if we go back to the table, we will subtract if we go this way, we add. So, 52 minus 4 is 48. The answer becomes 48. That is how you get it. If there’s one, just only one box that is given an actual age. Now, how will it be if I don’t know how to reconstruct the table? Can I do it another way? Yes, you can still get another chance. We will use trial and error. I’ll just erase these numbers here, except for 30 because it is given in the problem. How will you do trial and error? I’ll show you first using a wrong answer. Of course, we know that 52 is not the right answer because we’ve already know that 48 is the right answer. Now, what do you do? What we’re trying to find is how old is Leah’s Mother now. So, to the box of Leah’s Mother Now, you will put 52. So this becomes 52. If that’s 52, how old is she in 4 years? That is going to be 52 plus 4, becomes 56. Now, if Leah’s Mother is 56 in 4 years, how old is Leah now? We’ve said that we will multiply this with 2, when we’re reverting it back, we’ll do the exact opposite. Just like backtracking. So, to get Leah’s age now, divide this by 2,
56 divided by 2 is 28. If Leah is 28 now, how old is she in 4 years? That should be 28 + 4 which is 32, therefore she is not 30. As long as 30 won’t come out, that is not the correct answer. 52 is not the correct answer. Now, I’m going to try using a different colored pen. I’m going to show you that if you guess 48, it will turn out as the right answer. This is how. If I put in here 48, because this is how old is Leah’s Mother Now, Leah’s Mother Now is 48. I’ll be doing the exact same thing. If this is 48, plus 4 is 52 divided by 2, becomes 26 26 plus 4 is 30. So this is the same with what is given in the problem. So, what does that mean? 48 is really the correct answer. This time we’re going to use another type of problem. It’s different but it’s still age problem. We’re going to ask the same questions.
We’re going to build a table. First question, how many are the persons(tao)? The number of persons, again, determines the number of rows in our table. The number of time periods will determine the number of our columns. What we’re going to do is basically ask ourselves — how many persons were mentioned in the problem? It says “Barry’s age is twice Alex’s age now. Five times Alex’s age 2 years ago is equal to Barry’s age in 5 years. How old is Alex now?” So, there’s only two names mentioned, there are only two persons. You have Barry and Alex. So, there are two rows in our table, so, one… …two So, we have Alex, we have Barry. Now for the time periods… How many are the time periods? You have “is” which is in the present tense. You have “now”. So, definitely you have present tense. Now, we’re going to talk about the next time period mentioned. It says “Five times Alex’s age 2 years ago”. What does “2 years ago” mean? That is in the past. So, that’s our second time period. Is there anything else? It is stated here “in 5 years”, so that is in the future. So, you have present, past, future. There is nothing more because the “How old is Alex now?” is still in the present, so, it is not repeated. Definitely, you have past, present, future. Again, my suggestion is you write it like this… …past …present …and future. This is your “now”. Your now point is always zero. Then you have “2 years ago”. Two years ago in the past. That 2 years ago means it is subtracted by 2. The “in 5 years”, that is in the future. So, that means it is plus 5, okay? Now, again, now that we the table, we will fill it in with information from the problem. Okay, I’m sorry. There. Information on the problem, all we have to do is
put in all the information, okay? Now, it says “Barry’s age is…” “is”, so that means it is now, “twice Alex’s age now”. So, Barry’s age which is now, this here, is equal to the times 2 of Alex’s age now. So, Alex’s age now, this, when I multiply by 2 will result in Barry’s age now. Same thing that we did in the problem earlier. Next, it says “Five times…” what? “…Alex’s age 2 years ago”. So, the question is, where is Alex’s age 2 years ago?
Where’s the box for that? This one here. Alex’s age 2 years ago, this, multiplied by 5,
because it says here “Five times” of this. “Five times” is 5 times, will result in Barry’s age in 5 years. So, Barry’s age in 5 years, this one here. So, if you multiply this by 5, it should result in this. Okay? Now, we’ve written all the information on the table. We’re now going to use trial and error. The question is — “How old is Alex now?” All we have to do is,
all these information, we’re go through them one by one. We will put them in Alex now. And we’re going to reconstruct the table. Now, if you are not comfortable with that, if you want to use the equation, it’s going to be like this… How old is Alex now? This becomes your X, okay? This becomes X – 2. This becomes X times 2 or 2X. This becomes X times 2 plus 5. Your equation becomes ( X – 2 ) 5=X * 2 + 5. That is your equation. But, again, if cannot construct an equation, what do you do? You’re going to use your trial and error. I’ll just erase these, so we’ll have some space for our trial and error. I’m going to show you how to do it. I always suggest, if you’re going to use trial and error, don’t start with the largest or smallest of the choices. Because it is easier to eliminate if you use, let’s say, the second to the smallest or second to the largest number in the choices. The reason for that is, if you get an answer and it’s wrong, and it exceeded, then you will go down to the smaller among the choices. If, however, it was deficient,
then you will have to climb up to the larger among the choices. Then you’ll be able to start eliminating choices. So, it can save you some time, if you try using the second largest or second smallest number in the choices. So, in this case, we can try 10. We will try 10, we will use blue pen for that. If ten is the answer,
Alex’s age now becomes 10. If 10 is Alex’s age now, how old is he 2 years ago? That is 10 minus 2 or 8. If Alex is 10 now, Barry now becomes
10 times 2, which is 20. And Barry’s age in 5 years is 20 plus 5, this becomes 25. So, the question would be this,
if 8 multiplied by 5 will result in 25? Now, 8 times 5 is 40, it is not equal to 25 which should have been the result. So, that means 10 is wrong. It’s not the correct answer. Okay? Now, I’m going to use a different colored pen, we’ll just overlap just so you could see. The 10, we saw that it was too high. Because the 25 becomes a 40. So, let’s climb down. If we use, for example 5. If we make Alex 5 years old now… Don’t mind the blue ballpen, okay, the blue writings. Just focus on the greens. If Alex is 5 years old now, how old is he 2 years ago? He is 5 minus 2 years old, or 3. If Alex is 5 years now,
Barry is 5 times 2, which is 10. In 5 years, Barry who is 10 years old now becomes 15 years old. Now, question, this 3 if multiplied by 5 will result in 15? Yes, because if 3 times 5 is equal to 15, then it is now similar to the result here. Then that means C is the correct answer. So, again, if you use trial and error you would get to the correct answer. I’m going to ask you to try to answer this by yourself. All you need to do is to draw the table,
and then use trial and error to get to the correct answer. Okay? So, hit pause now. So, we’re going to use the techniques that we learned. Again, we’ll ask, how many tao (person)? how many time periods? First question, how many persons are there in our
problem? We have Sean and Jean. They are two. So, our rows are…
…one …two two rows, okay? You have Sean and Jean. Next question, how many are our time periods? You have “is”, okay? If we say “is”, it means now, because it is in present tense, right? What we’ll going to do next, if you have now, what else? You have “8 years from now”. That “8 years from now” is in the future. Eight years from now I will be older. It means that it is in the future. We have two time periods. There’s nothing else, because “will be” is same as the future, this “is” is still now. So, we have two columns. I really hope you got this table right.
If it’s just the table on your first try, that’s okay already. You have your Now, and then 8 years from now or plus 8. Now, it says in our problem that “Sean is 3 times as old as Jean. It means that Sean’s age is equal to 3 times that of Jean’s age. So if I multiply this by 3, Jean’s age,
it will result in Sean’s age. Okay, that is our first clue. Next, it says “8 years from now”,
so, that’s in the future, in this side, “Sean will be twice as old as Jean”. It means that, Sean will be,
this age, is equal to twice or times 2 of Jean’s age. So, times 2 of this will result in this, this circle. Question is, how old is Jean? If “how is Jean?”, it means that we are finding about Jean in the present. We’re going to use trial and error. Now, again, if you want to use traditional method, Jean becomes X, this becomes X * 3, this becomes (X * 3) + 8, this becomes X + 8. So our formula is going to be (X+8)2=(X*3)+8. Again, use this if you can construct an equation. But, if for example, you can’t really do it,
what do you do? We’re going to use trial and error. Using the same circles, we’re just going to fill in the number that you want to guess. Okay? So, for example, if we want to guess, didn’t I say that, if you want, you can start with the second highest or second lowest. So, let’s try 14. Because the question asks about Jean, we’ll put it here… …14. So, 14 times 3 is going to give you,
that is 42. Now, 8 years from now, the 42 years old will be 50 years old. Because 42 plus 8 is 50. This 14 years old, 14 plus 8 is going to give you 22. So, the question is,
is 22 times 2 will become 50? No, because it is only 44. So, 14 is not the correct answer. Not letter B. We eliminated that. Okay? So, what can we do next? We can use another number in the choices. I’m just going to change the color of my ink; erase these so we can have more space for our trial and error. Again, l use green. We can try 12. If Jean is 12 years old now, times 3, he’ll be 36 years old. Plus 8, this age, that is going to give 44 years old. 12 plus 8 is going to give you 20. Now, 20 times 2 is not 44. Okay? Because 20 times 2 is 40. So, it’s also not equal, so it also means that 12 is not the correct answer. We can try another color. Let’s make it 8. If Jean is 8 years old. Times 3 is… …24. Sean is 24. Now, in 8 years, Sean, who is 24, will be 32 years old. Jean, on the other hand, plus 8 also, will be 16 years old. Is 16 times 2 gives 32? Yes. So, because they are both 32,
they have the same results. The answer becomes letter C, 8. Again, what are the keys? Table and trial and error. Okay? Practice more, so you’ll be faster. Alright, I hope you learn something new today. If you did, click thumbs up. Make sure that you share this video to your friends, especially if they’re taking the exam like you. And as always, click subscribe if you’re watching this on YouTube, so that you’ll know as soon as a new video posts. If you have any questions or you want one of the reviewers or if you want to attend one of the library events, go to www.facebook.com/teamlyqa to find out all the details that you need. Thank you, guys. I’ll see you in my next video. Aja! Aja! You can do it! Bye for now. [music playing]