Quiz Discussion

The average age of group of 20 girls is 15 years and that of another group of 25 boys it is 24 years. The average age of the two groups mixed together is :

• 1] 19.5 yearas
• 2] 20 years
• 3] 21 yearas
• 4] 21.5 years

If the arithmetic mean of 0, 5, 4, 3 is a, that of -1, 0, 1, 5, 4, 3 is b and that of 5, 4, 3 is c, then the relation between a, b, and c is

• 1] a = b = c
• 2] a : b : c = 3 : 2 : 4
• 3] 4a = 5b = c
• 4] a + b + c = 12

Average of 80 numbers are 42. When 5 more numbers are included, the average of 85 numbers become 45. Find the average of 5 numbers.

• 1] 82
• 2] 89
• 3] 93
• 4] 98

If the mean of 4 observations is 20, when a constant 'c' is added to each observation, the mean becomes 22. The value of c is :

• 1]

  6

• 2]

  -2

• 3]

  2

• 4]

  4

The average wages of a worker during a fortnight comprising 15 consecutive working days was Rs. 90 per day. During the first 7 days, his average wages was Rs. 87/day and the average wages during the last 7 days was Rs. 92/day. What was his wage on the 8th day?

• 1] 93
• 2] 90
• 3] 92
• 4] 97

The average monthly salary of 12 workers and 3 managers in a factory was Rs. 600. When one of the manager whose salary was Rs. 720, was replaced with a new manager, then the average salary of the team went down to 580. What is the salary of the new manager?

• 1] 640
• 2] 690
• 3] 420
• 4] 570

The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero ?

• 1]

  0

• 2]

  -1

• 3]

  1

• 4]

  None Of These

When the average age of a couple and their son was 42 years, the son married and got a child after one year. When the child was 5 years old, the average age of the family became 36 years. What was the age of daughter-in- law at the time of their marriage ?

• 1] 23 years
• 2] 24 years
• 3] 25 years
• 4] 26 years

A train covers the first 16 km at a speed of 20 km per hour another 20 km at 40 km per hour and the last 10 km at 15 km per hour. Find the average speed for the entire journey.

• 1]

  24 km

• 2]

  26 km

• 3]

  21 km

• 4]

  km

Total expenses of a boarding house are partly fixed and partly varying linearly with the number of boarders. The average expense per boarder is Rs. 700 when there are 25 boarders and Rs. 600 when there are 50 boarders. What is the average expense per boarder when there are 100 boarders?

• 1] Rs. 540
• 2] Rs. 550
• 3] Rs. 570
• 4] Rs. 580