8. If the mean of 5 observation x, x+2, x+4, x+6 and x+8 is 11, then the mean of the last three observation is :

A.11

B.13

C.15

D.17

9. The average of th? two-digit numbers, which remain the same when the digits inter-change their positions, is :

A.33

B.44

C.55

D.66

10. The average of first 50 natural numbers is :

A.12.25

B.21.25

C.25

D.25.5

11. The average of all odd numbers upto 100 is :

A.49

B.49.5

C.50

D.51

12. If a, b, c, d, e are five consecutive odd numbers, their average is :

A.5 (a+4)

B.abcde/5

C.5(a+b+c+d+e)

D.None of these

13. The average of a non-zero number and its square is 5 times the number. The number is

A.9

B.17

C.29

D.295

14. The average of 7 consecutive nurnlers is 20. The largest of these nurnbers is :

A.20

B.22

C.23

D.24

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