Q446
The average of twelve numbers is 39. The average of the last five numbers is 35, and that of the first four numbers is 40. The fifth number is 6 less than the sixth number and 5 more than the seventh number. The average of the sixth and seventh numbers is:
A.
47.5
B.
44.5
AnswerC.
39
D.
50
Answer: Option B
Solution
Answer: Option B
Solution:
Sum of 12 numbers = 12 × 39 = 468Sum of last 5 numbers = 5 × 35 = 175
Sum of first 4 numbers = 4 × 40 = 160
\begin{array}{*{20}{c}} {{5^{{\text{th}}}}}&{{6^{{\text{th}}}}}&{{7^{{\text{th}}}}} \\ {\left( {x - 6} \right)}&{\left( x \right)}&{\left( {x - 11} \right)} \end{array}