# Quantitative Aptitude: Average Questions Set 6

1. In a Computer exam, a student scored 45% marks in the first paper out of a total of 200. How much should he score in the second paper out of a total of 250, if he is to get an overall average of 160/3%?
65%
70%
55%
60%
None
Option D
Solution:
Maximum mark =200+250=450
Let x% be scored in 2nd paper.
45/100*200 + x/100*250 =160/300*450
90+ x/100*250=240
x/100*250=240-90
x/100*250=150
x=60%.
2. The average of a group of men is increased by 8 years when a person aged of 22 years is replaced by a new person of aged 62 years. How many men are there in the group?
6
8
4
5
None
Option D
Solution:
Let n be the no. of persons in the group.
a-nd
62-8n=22
8n=40
n=5.
3. A car owner buys petrol at Rs.7.50, Rs.8, Rs.8.50 per litre for three consecutive years. What approximately is the average cost per litre if he spends Rs.4000 each year?
Rs6.35
Rs5.85
Rs7.98
Rs6.75
None
Option C
Solution:
Total quantity of petrol purchased
=4000/7.5+4000/8+4000/8.5
Total cost =4000*3
Average=(4000*3) /(4000/7.5+4000/8+4000/8.5)
=3/(1/7.5+1/8+1/8.5)
=Rs7.98.
4. The average age of three men A, B and C is 45, while the average age of three men B, D and E is 52 kg. What is the average age of A, B, C, D and E?
48
50
52
None
Option D
Solution:
5. The average age of a class is 30 yr.5 new students with an average age of 32 yr joined in that class, thereby increased the average by half year. The original strength of the class was
15
20
18
24
None
Option A
Solution:
Let the number of students in the class = x
30*x +5*32 /(x+5)=30+1/2
30x+160/(x+5)=61/2
x=15.
6. Average cost of 5 pen and 4 pencil is Rs. 36. The average cost of 7 pen and 8 pencil is Rs. 48. Find the total cost of 36 pen and 36 pencil.
3445
3132
3320
3543
None
Option B
Solution:
Average cost of 5 pen and 4 pencil = Rs. 36.
Total cost = 36 * 9 = 324.
Average cost of 7 pen and 8 pencil = 48.
Total cost = 48 * 15 = 720.
Total cost of 12 pen and 12 pencil = 324 + 720 = 1044.
Then, cost of 36 pen and 36 pencil = 1044 * 3 = 3132.
7. The average age of four student is 15. If age 18 was misread as 10 during the calculation, what will be the correct average?
17
18
20
16
None
Option A
Solution:
18-10=8 age is missing.
Then correct average= 15+ 8/4
=15+2
=17.
8. The average age of a husband and wife was 23 when they were married 5 years ago. The average age of the husband, the wife and a child who was born during the interval, is 20 years now. How old is the child now?
8years
4years
6years
10years
None
Option B
Solution:
Present total age of husband and wife
= (23 * 2 + 5 * 2) = 56
Present total age of husband, wife and child
= 20 * 3 = 60 years
Age of child = (60 – 56) = 4 years.
9. Distance between two stations A and B is 630 km. A train covers the journey from A to B at 54 km per hour and returns back to A with a uniform speed of 36km per hour. Find the average speed of the train during the whole journey?
43.2
44
46.5
41
None
Option A
Solution:
Distance same then average=2xy/(x+y)
=2*54*36 /(54+36)
=2*54*36/90
=43.2.
10. Students of three different classes appeared in exam. Pass average of 20 students of first class was 60%, pass average of 30 students of second class was 70% and pass average of 40 students of third class was 80% then what will be the approximate pass average of all students of three classes?
62%
66%
72%
76%
None
Option C
Solution:
Sum of pass students of first, second and third class,
= (60% of 20) + (70% of 30)+ (80% of 40)
= 12+21+32 = 65
Total students appeared,
= 20+30+40 = 90
Pass average,
90…. 100
65 …. ? ==>72%(approx).