Quiz Discussion

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 age of the boys in a class is 16 years and that of the girls is 15 years. The average age for the whole class is-

• 1] 15 years
• 2] 15.5 years
• 3] 16 years
• 4] Cannot be computed with the given information

Average weight of 25 students of a class is 50 kg. If the weight of the class teacher is included , the average is increased by 1 kg. The weight of the teacher is ?

• 1] 76 kg
• 2] 77 kg
• 3] 74 kg
• 4] 75 kg

Of the three numbers, the first is twice the second and the second is twice the third. The average of the reciprocal of the numbers is 7/72. The numbers are:

• 1] 36, 18, 9
• 2] 24, 12, 6
• 3] 20, 10, 5
• 4] 16, 8, 4

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

The average score of a cricketer for ten matches is 38.9 runs. If the average for the first six matches is 42, then find the average for the last four matches.

• 1] 33.25
• 2] 33.5
• 3] 34.25
• 4] 35

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

The average age of husband and his wife was 23 years at the time of their marriage. After five tears they have a one-year old child. The average age of the family of three, when the child was born, was-

• 1] 23 years
• 2] 24 years
• 3] 18 years
• 4] 20 years

The average pocket money of 3 friend A, B, C is Rs. 80 in a particular month. If B spends double and C spends triple of what A spends during that month and if the average of their unspent pocket money is Rs. 60, then A spends (in Rs.)-

• 1] Rs. 10
• 2] Rs. 20
• 3] Rs. 30
• 4] Rs. 40

Out of 9 persons, 8 persons spent Rs. 30 on each of their meals. The ninth one spends Rs. 20 more than the average expenditure of all the nine. The total money spent by all of them was

• 1]

  Rs 260

• 2]

  Rs 290

• 3]

  Rs 292.5

• 4]

  Rs 400.5