There are thirteen 2-digit consecutive odd numbers. If 39 is the mean of the first five such numbers, then what is the mean of all the thirteen numbers?
There are thirteen 2-digit consecutive odd numbers. If 39 is the mean of the first five such numbers, then what is the mean of all the thirteen numbers? Correct Answer 47
Given :
There are thirteen 2-digit consecutive odd numbers.
39 is the mean of the first five such numbers.
Formula used :
Average = Sum of all observations/Number of observations
Calculations :
Let the number be 2x + 1, (2x + 3), (2x + 5), ...........(2x + 25)
According to the question
(2x + 1 + 2x + 3 + 2x + 5 + 2x + 7 + 2x + 9)/5 = 39 (Average of the first five numbers)
x = 17
So numbers are 35, 37, 39, ..............59
Average of all 13 numbers = (35 + 37 + 39 ..........+ 59)/13
⇒ 611/13
⇒ 47
∴ The average of all numbers will be 47.
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Feb 20, 2025