Transcription
Welcome to the third in this series of age word problems. And I just wanted to start off where I left off in the second one. I got myself confused. You guys make me very nervous while you just sit there listening and I have to perform for you. But, it turns out we did get the right answer; if you say Arman is 153 and Tarush is 765, then 85 years ago Arman would have been 68 and Tarush would have been 680. And notice that's 10 times. So it worked out. So we're ready to tackle another problem.
One more problem. Let's see. This problem says, Zack is 4 times as old as Salman. What a coincidence. Salman really shows up in a lot of problems. So Zack is 4 times as old as Salman. Zack is also 3 years older than Salman. How old is Zack? Well, actually this one actually seems fairly straightforward. We're not dealing with the present and the future; we're just dealing with the present. So let's see if we can figure this out.
So we're trying to figure out how old is Zack. Let's say, z for Zack. z equals Zack. It says Zack is 4 times as old as Salman. So, Salman, if Zack is z, this first sentence, let me circle it: Zack is 4 times as old as Salman. So, if Zack is 4 times as old as Salman, that means that Sal is equal to Zack divided by 4. But then it also says here that Zack is also 3 years older than Salman. Well, if Zack is also 3 years older than Salman, so that means that also Sal would be Zack minus 3. The first sentence says Zack is 4 times as old as Salman. So that means if you take Zack's age and divide it by 4, you get Sal's age. The second sentence says Zack is also 3 years older than Salman. So that means if you take Zack's age and you subtract 3 from it, you get Sal's age again.
Well, we have our equation set up. And, actually, instead of writing Zack, I should have just written z. But the equation is all set up for us. We get z over 4 is equal to z minus 3. We can multiply both sides of this equation times 4 and we'll get z is equal to 4z, remember to distribute, minus 12. And then, we'll skip a couple of steps. And I get 3z is equal to 12. And I get Zack is equal to 4 years old.
Let's see if that makes sense. If Zack is 4 years old, then this first sentence says Zack is 4 times as old as Salman. So that means Sal is 1 year old. It also says Zack is 3 years older than Salman. Well, that's consistent. 4 is 3 more than 1. So we were right. Zack is exactly four years old.
Hope that helps. Have fun. I think you're ready. You've now seen, at least, every type of the age word problems. If you're still a little confused, you might just want to re-watch the videos and maybe pause it right after I give you the problem, and see if you can solve it yourself. And remember, you had a lot of practice problems that you can do on the actual modules themselves. Have fun.