Question

The average of a, b, c and d is 15. If the average of a and b is 7, then what will be the average of c and d?

Answer 1

Answer:

Average of c and d is 23

Step-by-step explanation:

Average = Sum of observations / No. of observations

Sum of observations = No. of observations * Average

Average of a, b, c and d = 15

=> (a + b + c + d) = 15*4  .......(no. of observations is 4)

=> (a + b + c + d) = 60 .......(i)

Average of a and b = 7

=> (a + b) = 7*2           ...(no. of observations is 2)

=> (a + b) = 14 .........(ii)

Using (ii) in (i),  we get:

14 + (c + d) = 60

=> (c + d) = 60 - 14

=> (c + d) = 46

=> (c + d)/2 = 23

=> Average of c and d is 23

Answer 2

Step-by-step explanation:

-8×2+2x =0

x=8

average of c,d =23