Quiz Discussion

The arithmetic mean of the scores of a group of students in a test was 52. The brightest 20% of them secured a mean score of 80 and the dullest 25% a mean score of 31. The mean score of remaining 55% is-

• 1] 45
• 2] 50
• 3] 51.4 approx
• 4] 54.6 approx

Find the average of all prime numbers between 30 and 50.

• 1]

  37.8

• 2]

  38.9

• 3]

  39.8

• 4]

  42.8

The average age of A, B, C, D and E is 40 years. The average age of A and B is 35 years and the average of C and D is 42 years. Age of E is :

• 1] 48 years
• 2] 46 years
• 3] 42 years
• 4] 45 years

The average height of 30 boys out of a class of 50 is 160 cm. If the average height of the remaining boys is 165 cm, the average height of the whole class (in cm) is :

• 1] 161
• 2] 162
• 3] 163
• 4] 164

The average of four consecutive even numbers is 15. The 2nd highest number is :

• 1] 12
• 2] 18
• 3] 14
• 4] 16

40% of the employees in a factory are workers. All the remaining employees are executives. The annual income of each worker is Rs. 390. The annual income of each executive is Rs. 420. What is the average annual income of all the employees in the factory together?

• 1] 390
• 2] 405
• 3] 408
• 4] 415

The average weight of 10 oarsmen in a boat is increased by 1.5kg when one of the crew who weighs 58kg is replaced by a new man.

• 1]

  73 Kg

• 2]

  64 Kg

• 3]

  12 Kg

• 4]

  34 Kg

If the mean of a,b,c is M and ab+bc+ca=0, then the mean of a²,b²,c² is:

• 1]

  M²

• 2]

  3M²

• 3]

  6M²

• 4]

  9M²

The average of the first five multiples of 3 is-

• 1] 3
• 2] 9
• 3] 12
• 4] 15

Out of four numbers the average of the first three is 16 and that of the last three is 15. If the last number is 20, than first number is :

• 1] 25
• 2] 21
• 3] 23
• 4] 28