The average of thirteen numbers is 47. The average of the first three
| The average of thirteen numbers is 47. The average of the first three numbers is 39 and that of next seven numbers is 49. The 11th number is two times the 12th number and 12th number is 3 less than the 13th number. What is the average of 11th and 13th number ?
A. 55 . 5
B. 57
C. 54 . 5
D. 56
Right Answer is: B
SOLUTION
A. T. Q.
Let the 12th no. be =
Hence the 11th no. = 2
13th no. =
It is given that
By solving, we get
Required
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The average of thirteen numbers is 47. The average of the first three