MathRevolution wrote:
[
Math Revolution GMAT math practice question]
The average (arithmetic mean) of the five numbers in a data set is 72. The average (arithmetic mean) of the first three numbers is 98. What is the average (arithmetic mean) of the last two numbers?
A. 31
B. 32
C. 33
D. 34
E. 35
Sum = (quantity)(average).
The average (arithmetic mean) of the five numbers in a data set is 72.Sum = 5*72 = integer with a UNITS DIGIT OF 0.
The average (arithmetic mean) of the first three numbers is 98.
Sum = 3*98 = integer with a UNITS DIGIT OF 4.
For the sum of all 5 numbers to have a units digit of 0, the sum of the remaining 2 numbers must have a UNITS DIGIT OF 6, since INTEGER WITH A UNITS DIGIT OF 6 + INTEGER WITH A UNITS DIGIT OF 4 = INTEGER WITH A UNITS DIGIT OF 0.
Only C will yield for the other 2 numbers a sum with a units digit of 6:
2*33 = 66.
_________________
GMAT and GRE Tutor
Over 1800 followers
GMATGuruNY@gmail.com
New York, NY
If you find one of my posts helpful, please take a moment to click on the "Kudos" icon.
Available for tutoring in NYC and long-distance.
For more information, please email me at GMATGuruNY@gmail.com.