Question

Mean of four numbers a ,b, c, and d is 8 and mean of seven

numbers x , y ,z ,a, b, c and d is 12 . Find the mean of x, y and z.

Answer 1

• 17 1/3 or 17.33

Explanation:

Mean of four numbers a, b, c, and d is 8:

• (a + b + c + d)/4 = 8
• ⇒ a + b + c + d = 32

Mean of seven numbers x, y, z, a, b, c and d is 12:

• (x + y + z + a + b + c + d)/7 = 12

Substitute the sum of 4 numbers:

• x + y + z + 32 = 7*12
• x + y + z = 84 - 32
• x + y + z = 52

Mean of x, y and z is:

• 52/3 = 17 1/3 or 17.33