Question
The average of 30 numbers is 1.2. The average of the
first 20 of them is 1.1 and that of the next 9 is 1. Then the last number is:Solution
The total sum of 30 numbers= 30 x 1.2= 36 The sum of the first 20 numbers= 20 x 1.1= 22 The sum of the next 9 numbers= 9×1=9 Last number= 36-22-9=5 The last number is 5.
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