Problem Solving

swerve wrote:Eleven years ago Tina was half as old as Ike will be in 4 years. If Ike is m years old now, how old is Tina now, in terms of m?

A. 4m - 11
B. m/2 + 13
C. 1/(2m - 22)
D. (4m + 11)/2
E. 2m - 7

The OA is B

Source: Economist GMAT

Say Tina's current age is T years.

Thus, T - 11 = (m + 4)/2

T = (m + 4)/2 + 11 = m/2 + 13

The correct answer: B

Hope this helps!

-Jay
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swerve wrote:Eleven years ago Tina was half as old as Ike will be in 4 years. If Ike is m years old now, how old is Tina now, in terms of m?

A. 4m - 11
B. m/2 + 13
C. 1/(2m - 22)
D. (4m + 11)/2
E. 2m - 7

The OA is B

Source: Economist GMAT

Let's let T = Tina's age now. Thus, eleven years ago, Tina was (T - 11) years old. In 4 years, Ike will be (m + 4) years old. We can create the equation:

T - 11 = 1/2(m + 4)

2T - 22 = m + 4

2T = m + 26

T = m/2 + 13

Answer: B

swerve wrote:Eleven years ago Tina was half as old as Ike will be in 4 years. If Ike is m years old now, how old is Tina now, in terms of m?

A. 4m - 11
B. m/2 + 13
C. 1/(2m - 22)
D. (4m + 11)/2
E. 2m - 7

Given: m = Ike's PRESENT age
So, m + 4 = Ike's age IN 4 YEARS
So, (1/2)(m + 4) = Tina's age 11 YEARS AGO
So, (1/2)(m + 4) + 11 = Tina's PRESENT age

The answer does not appear among the answer choices. So, we'll need to SIMPLIFY the expression
Take: (1/2)(m + 4) + 11
Expand: m/2 + 2 + 11
Simplify: m/2 + 13

Answer: B

Cheers,
Brent