Mehmut's Present Age

[harpazo]

Mehmut is 4 times as old as his brother, but
next year he will be only 3 times as old. Find
Mehmut's age now?

Solution

Let M = Mehmut
Let b = brother

M = 4b

When the question states "...but
next year he will be only 3 times as old" I am thinking of adding 1 to Mehmut and his brother (number 1 representing one more year).

Anyway, here is my set up:

M = 4b
M + 1 = 3(4b + 1)

Correct set up?

 

[Dr.Peterson]

Close.

Read through that second equation and tell us what it means -- see if you can explain each part.

By the way, I'd say "M = Mehmut's age now (in years)" for clarity.

 

[Otis]

Let M = Mehmut
Let b = brother

That's too sloppy, harpazo. Do symbols M and b represent numbers?

 

[harpazo]

That's too sloppy, harpazo. Do symbols M and b represent numbers?

M = Mehmut's present age
b = Mehmut brother's age

 

[Steven G]

M = Mehmut's present age
b = Mehmut brother's age

That is better, but I think that you should say that M = Mehmut's age now and b = brother's age now.

 

[harpazo]

Close.

Read through that second equation and tell us what it means -- see if you can explain each part.

By the way, I'd say "M = Mehmut's age now (in years)" for clarity.

Second Equation Interpretation

M + 1 = 3(4b + 1)

M + 1 means Mehmut's age one year later.

4b = Mehmut is 4 times as old as his brother.

In place of (4b + 1), it should be (b + 1), which indicates Mehmut's brother one year later in terms of age. That is multiplied by 3 as indicated in the question.


M = 4b
M + 1 = 3(b + 1)

Is that better?

 

[Steven G]

Yes, that is better.

 

[Dr.Peterson]

Good. This is something I often tell students to do: Whenever you write anything, read it back and see if it really says what you wanted to say. If people did this regularly, they would make far fewer mistakes.

That also applies to people who write here and fail to proofread. People say a lot of nonsense when they don't take that time.

 

[Otis]

… That also applies to people who write here and fail to proofread. People say a lot of nonsense when they don't take that time.

Agree! Convenience and success have always been inversely related -- the digital age simply provides more proof.

 

[harpazo]

M = 4b...Equation A
M + 1 = 3(b + 1)....Equation B

Replace M in B with 4b and solve for b.

4b + 1 = 3b + 3

4b - 3b = 3 - 1

b = 2

Now plug b = 2 into EITHER A or B to find the value of M.

M = 4b

M = 4(2)

M = 8

Mehmut is now 8 years old.