Average

JKSSB Sub-Inspector (Executive) · Mathematics · 38 practice questions with answers and explanations: 13 Easy, 14 Medium, 11 Hard.

Sample questions

Sample Easy question 1

Find the average of 11, 12, 13, 14 and 15.

  1. 12
  2. 13
  3. 14
  4. 15
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Answer: B. Sum = 65, average = 65/5 = 13.

Sample Medium question 2

A car travels from city A to city B at 40 km/h and returns at 60 km/h. Find its average speed for the entire journey.

  1. 46
  2. 48
  3. 50
  4. 52
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Answer: B. Average speed for a round trip = 2xy/(x+y) = 2×40×60/100 = 48 km/h (not the simple average of the two speeds).

Sample Hard question 3

The average age of a family of 5 members is 24 years. The youngest member is 8 years old. What was the average age of the family at the time of the youngest member's birth?

  1. 18
  2. 19
  3. 20
  4. 21
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Answer: C. Current sum = 120. 8 years ago, the other 4 members' combined age was (120-8) - 4×8 = 80, giving an average of 20.

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