# The average of a set of numbers A is 85 and the average of a set B is 64. If set A has 4 times as many elements as set B, what is the average value of all the elements in both the sets.

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### 1 Answer

Set A has 4 times as many elements as set B. The average value of the elements of set A is 85 and the average value of the elements of set B is 64.

Let N denote the number of elements in set B, the number of elements in set A is 4*N. The total number of elements in both the sets put together is 5*N.

The total value of the elements of set A is 340*N and the total value of the elements of set B is 64*N. This gives the required average as `(340*N + 64*N)/(5*N) = 80.8`

**The required average is 80.8**