MathRevolution wrote:

[GMAT math practice question]

The range of the daily minimum temperatures in January is \(10^o\), and the range of the daily minimum temperatures in February is \(15^o\). What is the smallest possible range of the daily minimum temperatures in January and February combined?

A. \(5^o\)

B. \(10^o\)

C. \(15^o\)

D. \(20^o\)

E. \(25^o\)

Given \(Jan_{max}-Jan_{min}=10\)

\(Feb_{max}-Feb_{min}=15\)

Now max and min temperatures during Jan & Feb combined are fixed. Let's assume max temperature occurred in Feb

So smallest range for these two months: \(Feb_{max}-Min=Range\)----------------(1). Here if Min value is low then range will be high and there are two min values possible, \(Jan_{min}\) & \(Feb_{min}\)

Now to make the range as small as possible \(Jan_{min}=Feb_{min}\) because if Min value of equation (1) is lower than \(Feb_{min}\) then the range of equation (1) will be higher than \(15\)

Hence smallest range possible is \(15\)

Option

C