Averages (200 Questions with Explanation): Quantitative Aptitude Test

426.

The average age of a group of 10 students was 18. The average age increased by 1 years when two new students joined the group. What is the average age of the two new students who joined the group?

   A.) 15.5
   B.) 12.5
   C.) 24
   D.) 16.5

Answer: Option 'C'

The average age of a group of 10 students is 18.
Therefore, the sum of the ages of all 10 of them = 10 * 18 = 180
When two students joins the group, the average increase by 1.
New Average = 19 Now there are 12 students Therefore, sum of all the ages of 12 students = 228
Therefore, the sum of the ages of two students who joined = 228 - 180 = 48
And the average age of these two students = 24

427.

The average of 16 numbers is zero. Of them, at the most how many may be greater than zero?

   A.) 17
   B.) 15
   C.) 14
   D.) 8

Answer: Option 'B'

Average of 16 numbers is = 0 Therefore sum of all 16 numbers = 0
It is quite possible that 15 of these numbers may be positive and if their sum is "a" then 16th number is "(-a)".


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