Home > Practice > Arithmetic Aptitude > Average > Miscellaneous
21. A school has only four classes that contain 10, 20, 30 and 40 students respectively. The pass percentage of these classes are 20%, 30%, 60% and 100% respectively. Find the pass % of the entire school.

Discuss
Solution:
The number of pass candidates are 2 + 6 + 18 + 40 = 66 out of total 100.
Hence, Pass percentage = 66%
22. 19 people went to a hotel for combine dinner party 13 of them spent Rs. 79 each on their dinner and rest spent 4 more than the average expenditure of all the 19. What was the total money spent by them.

Discuss
Solution:
Let average expenditure of 19 people be x
then,
19x = 13 × 79 + 6 × (x + 4)
or, 19x = 13 × 79 + 6x + 24
or, x = 80.84
So, total money spent
= 80.84 × 19
= Rs. 1536.07
23. The average weight of 47 balls is 4 g. if the weight of the bag (in which the balls are kept) be included; the calculated average weight per ball increases by 0.3 g. What is the weight of the bag?

Discuss
Solution:
Total increased weight
= 0.3 × 47
= 14.1 g
24. A cricketer scored some runs in his 21st innings, as a result, his average runs increased by 3. If the present average run is 40, how many runs he scored in the final innings?

Discuss
Solution:
Let he scored x runs in final innings
Now,
37 × 20 + x = 40 × 21
x = 840 - 740
x = 100
25. Ajay working in a Cellular company as a salesman. His monthly salary is Rs. 200. But he gets bonus as per given rule. If he sells sim cards of Rs. X then his bonus will be [(x100)2+10]   . In the first quarter of the year his average sale was Rs. 3000 per month. In the next 5 five month his average sale was Rs. 5000 per month and for next four month his average sale was Rs. 8000 per month. What is the average earning per month for the whole year?

Discuss
Solution:
Bonusforthefirstthreemonth,=[(3000100)2+10]×3=Rs.2710Bonusforthenextfivemonth,=[(5000100)2+10]×5=Rs.12550Bonusforthenextfourmonth,=[(8000100)2+10]×4=Rs.25640Totalearningasbonusforwholeyear,=2710+12550+25640=Rs.40900Hisaveragebonus=4090012=Rs.3410Thushisaverageearningforwholeyear,=3410+200=Rs.3610
26. A man has 'n' magical eggs whose average weight is 'k' gm. Each of the 'n' eggs produces 'n' eggs next day such that the average weight of 'n' eggs produced is same as that of the parental egg for each 'n' groups individually i.e. each egg produces 'n' eggs of next generation and average weight of all the 'n' eggs of next generation is same as the weight of the mother egg. This process is continued without any change in pattern. What is the total weight of all the eggs of rth generation, where the initial number of eggs with man are considered as the eggs of first generation.

Discuss
Solution:
The weight is increasing in form of GP so the total weight of eggs in the end of rth will be nrk.
27. A man started his journey from Lucknow to Kolkata, which is 200 km, at the speed of 40 kmph then he went to Banglore which is 300 km, at the speed of 20 kmph. Further he went to Ahmedabad which is 500 km, at the speed of 10 kmph. The average speed of the man is :

Discuss
Solution:
Averagespeed,=TotalDistanceTotaltime=200+300+50020040+30020+50010=100070=1427kmph
28. 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 :

Discuss
Solution:
A + B + C + D + E = 40 × 5 = 200
A + B = 35 × 2 = 70
C + D = 42 × 2 = 84
Therefore,
E = (A + B + C + D + E) - (A + B + C + D)
E = 200 - 70 - 84
E = 46 years
29. The mean weight of 100 students in a class is 46 kg. The mean weight of boys is 50 and of girls is 40 kg. Therefore, the number of boys is:

Discuss
Solution:
Let number of boys are x and then number of girls
= (100 - x)
Thus,
50x + (100 - x) × 40 = 46 × 100
→ x = 60
Number of boys = 60
30. There are three categories of jobs A, B and C. The average salary of the student who got the job of A and B categories is 26 lakh per annum. The average salary of the students who got the job of B and C category is 44 lakh per annum and the average salary of those students who got the job of A and C categories is 34 lakh per annum. The most appropriate (or closet) range of average salary of all the three categories (if it is known that each student gets only one category of jobs i.e. , A, B and C):

Discuss
Solution:
Let the number of students who got the job of A, B and C categories is a, b and c respectively,
Then the total salary,
={26(a+b)+44(b+c)+34(c+a)}2(a+b+c)
=(60a+70b+78c)2(a+b+c)=[30(a+b+c)+(5b+9c)](a+b+c)
= 30 + some positive value
Thus, the minimum salary must be Rs. 30 lakh and the maximum salary can not exceed 44,
which is the highest of the three

Previous

Next