Word Problem

[phoenix9801]

Please explain in details how to solve this problem using Only plug in numbers not algebraically. Use simple numbers. Be simple. Thanks


Eleven years ago, Lauren was half as old as Mike will be in 4 years. If Mike is m years old now, how old is Lauren now in terms m ?

a) 4m-11
b) 1/2(m+4)+11
c) 1/2(m-11)
d) 4m+ 11/2
e) 2m-7

[GMATGuruNY]

Please explain in details how to solve this problem using Only plug in numbers not algebraically. Use simple numbers. Be simple. Thanks


Eleven years ago, Lauren was half as old as Mike will be in 4 years. If Mike is m years old now, how old is Lauren now in terms m ?

a) 4m-11
b) 1/2(m+4)+11
c) 1/2(m-11)
d) 4m+ 11/2
e) 2m-7

Let M=10.
In 4 years, M = 10+4 = 14.
11 years ago, L = (1/2)14 = 7.
Thus, L now = 7+11 = 18. This is our target.

Now we plug M=10 into the answers to see which yields our target of 18.

Only B works:
(1/2)(M+4) + 11 = (1/2)(10+4) + 11 = 18.

The correct answer is B.