Question

B) The average of 9 numbers is 23. If the average of first five numbers is 20 and

that of last five numbers is 25, what is the fifth number?

NEXT QUESTION:

c) The average age of a husband and wife was 23 years at the time of their
marriage. After 10 years, they have now a daughter of 6 years, what is he
average age of the family at present?
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Answer 1

b)

Explanation:

As here it's stated that average of first 9 numbers is 23

so,

sum of 9 numbers = 9×23 = 207

Average of first 5 numbers is 20

so,

Sum of first 5 numbers = 5×20 = 100

Sum of remaining numbers = 207-100 = 107

Average of last five numbers = 25

So,

Sum of last five numbers = 5×25 = 125

Fifth Number = Sum of last five numbers- Sum of remaining numbers

= 125 - 107 = 18