Quant Quiz - Average

Q1)-Nine persons went to a hotel for taking their meals. Eight of them spent Rs 12 each on their meals and the ninth spent Rs 8 more than the average expenditure of all the nine. What was the total money spent by them ?

Rs 97

Rs 117

Rs 107

Rs 87

Ans.- B
Let the average expenditure of all the nine be Rs x.
Then, 12 X 8 + (x + 8) =9x or 8x = 104 or x =13
Total money spent = 9x = Rs ( 9 X 13 ) = Rs 117

Q2)-Of the three numbers , second is twice the first and is also thrice the third . If the average of the three numbers is 44. Find the largest number.

60

64

72

44

Ans.- C
Let the third number be x. Then, second number = 3x. First number = 3x/2
x + 3x + 3x/2 = (44 X 3) or x = 24
So , largest number = 2nd number = 3x =72

Q3)-The average of 25 results is 18. The average of first twelve of them is 14 and that of last twelve is 17.Find the thirteenth result.

68

78

88

98

Ans.- B
Thirteenth result = (sum of 25 results) - (sum of 24 results )
= (18 X 25 ) - [(14 X 12) + (17 X 12)]=78

Q4)-The average of 11 results is 60. If the average of first six results is 58 and that of the last six is 63. Find the sixth result.

55

66

77

67

Ans.- B
Sixth result = ( 58 X 6 + 63 X 6 - 60 X 11 )=66

Q5)-The average weight of A , B , C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, Find the weight of B.

30 kg

31 kg

32 kg

33 kg

Ans.- B
Let A, B and C represent their individual weights. Then, A + B + V = (45 X 3 ) kg = 135 kg
A + B = (40 X 2) kg =80 kg and B + C = (43 X 2) kg= 86 kg
B = ( A + B ) + (B + C ) - ( A + B + C) = 31 kg

Q6)-The average age of a class of 39 students is 15 years. If the age of the teacher be included, then the average increases by 3 months. Find the age of the teacher.

40 years

35 years

30 years

25 years

Ans.- D
Total age of 39 persons = ( 39 X 15 ) years = 585 years.
Average age of 40 persons = 61/4 years.
Total age of 40 persons = (61/4 X 40) = 610 years
Age of the teacher = ( 610 - 585 ) years = 25 years

Q7)-The average weight of 10 oarsmen in a boat is increased by 1.8 kg when one of the crew , who weighs 53 kg is replaced by a new man. Find the weight of the new man.

18 kg

89 kg

71 kg

80 kg

Ans.- C
Total weight increased = (1.8 X 10 ) kg = 18 kg
Weight of the new man = ( 53 + 18 ) kg = 71 kg

Q8)-There were 35 students in a hostel. Due to the admission of 7 new students, the expenses of the mess were increased by Rs 42 per day while the average expenditure per head diminished by Re 1. What was the original expenditure of the mess ?

Rs 400

Rs 450

Rs 350

Rs 420

Ans.- D
Let the original average expenditure be Rs x. Then , 42 (x-1) - 35x = 42
x = 12
Original expenditure = Rs ( 35 X 12 ) = Rs 420

Q9)-A batsman makes a score of 87 runs in the 17 th inning and thus increases his average by 3. Find his average after 17th inning.

38

39

37

40

Ans.- B
Let the average after 17th inning = x.
Then , average after 16th inning = ( x - 3)
16(x - 3) + 87 = 17x
x = 39

Q10)-Distance between two stations A and B is 778 km. A train covers the journey from A to B at 84 km per hour and returns back to A with a uniform speed of 56 km per hour. Find the average speed of the train during the whole journey.

66 km/h

67 km/h

67. 2 km/h

66.2 km/h

Ans.- C
Required average speed = (2xy)/(x+y) = (2 X 84 X 56)/140 = 67.2 km/h