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If the arithmetic mean of the following ...

If the arithmetic mean of the following data is 7, then a + b =
`{:(x_(i), 4,6,7,9),(f_(i)"",a,4,b,5):}`

A

4

B

2

C

3

D

cannot be determined

Text Solution

Verified by Experts

The correct Answer is:
D
We have,
`7=(4a+24+7b+45)/(a+4+b+5)`
`rArr 4a+7b+69=7a+7b+63 rArr a=2`
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OBJECTIVE RD SHARMA-MEASURES OF CENTRAL TENDENCY-Section I - Solved Mcqs
  1. The arithmetic of 12 observations is 15. If two observations 20 and ...

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  2. If the average of a, b, c and d is the average of b and c, then whic...

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  3. If the arithmetic mean of the following data is 7, then a + b = {:(x...

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  4. The average of n numbers x(1),x(2), …,x(n) is M. If x(n) is replaced b...

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  5. For a symmetrical distribution Q(1) =20 and Q(3) =40. The value of 5...

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  6. The mean of the series a, a + d, a + 2d, …, a + 2 nd, is

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  7. If the mean of the following data is 5.5, then x = {:(x(i),2,4,6,...

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  8. The median of the data 5 , 6 , 7, 8 , 9 , 10 is "".

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  9. The Median of the following discrete series is {:(x(i),3,6,5,8,12,...

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  10. The median class in the following frequency distribution is {:("Cla...

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  11. The number of observations in a group is 40. If the average of first 1...

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  12. GM of the numbers 3,3^2,3^3,...,3^n is

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  13. If the median of 25 observations is 45 and if the observations greater...

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  14. The median of a set of a observations is 20.5. If each of the largest ...

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  15. A boy goes to a school from his home at a speed of x km/hr and comes b...

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  16. A car complete the first half of its journey with speed v1, and the re...

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  18. The mode of the following distribution is {:("Class interval :",1-5...

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  19. The median of 100 observations grouped in classes of equal width is 25...

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  20. The age distribution of 400 persons in a colony having median age 3...

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