Question

A , b , c and d are different positive numbers. The average (arithmetic mean) of a and b is 30. The average of a , b , c and d is 40.

Answer 1

The average (arithmetic mean) of c and d is 50

Step-by-step explanation:

A , b , c and d are different positive numbers

The average (arithmetic mean) of a and b is 30

=> Sum of a and b = 2 * 30

=> a + b = 60

The average of a , b , c and d is 40.

=> Sum of a , b , c & d = 4 * 40

=> a + b + c + d = 160

(a + b + c + d) - (a + b) = 160 - 60

=> c + d = 100

The average (arithmetic mean) of c and d is 100/2  = 50

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