Question

In seven given numbers, the average of first four
numbers is 4 and that of last four numbers is also 4. If
the average of these seven numbers is 3, the fourth
number is
(a)3
(b) 4
(c) 7
(d) 11​

Answer 1

Answer:

let 7 numbers are a,b,c,d,e,f,g.

given avg of first 4 nums are 4...i.e (a+b+c+d)/4=4

a+b+c+d=16

given avg of last 4 nums are also 4..i.e.(d+e+f+g)/4=4

d+e+f+g=16

e+f+g=16-d

given avg of 7 nums are 3....i.e (a+b+c+d+e+f+g)/7=3

a+b+c+d+e+f+g=21

16+16-d=21

d=32-21

d=11 is answer