Aptitude AveragePage 2
9. | The sales recorded by a salesman in 6 days of a week were as follows:
Rs 20000 per day of the first 3 days. Rs 16000 on Thursday, Rs 24000 on Friday and on Saturday it was Rs 30000. Find his average sales per day? | | (a)21000 | | (b)21667 | | (c)21867 | | (d)20000 |
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Answer is: BAverage sales per day = [(20000 x 3) + 16000 + 24000 + 30000]/6 = 21667
10. | | The average age of a group of friends is 34 years. If five new friends with an average age of 30 years join the group, the average of the entire group becomes 32 years. How many people were there in the group initially? | | (a)4 | | (b)6 | | (c)7 | | (d)5 |
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Answer is: DLet there be 'n' people initially in the group. Then the total age of the group after the five new friends join the group is = 34n + (5 x 30)
But this is also equal to 32(n +5)
∴ 32(n +5) = 34n + 150
⇒ n = 5
So, there were 5 friends in the group initially.
11. | | If 20 kg of wheat costing Rs 16 a kg is mixed with 16 kg of a second variety of wheat costing Rs 25 a kg, then what is the average cost of the resulting mixture? | | (a)20 | | (b)21 | | (c)22 | | (d)23 |
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Answer is: AApplying weighted average rule,
the average of the mixture is = [(20 x 16) + (16 x 25)]/(20 + 16).
the average of the mixture is = 720/36 = Rs 20 a kg.
12. | | If two kinds of grapes costing Rs 16 a kg and Rs 21 a kg are mixed in the ratio of 2 : 3, then find the cost of mixture per kg? | | (a)20 | | (b)19 | | (c)21 | | (d)23 |
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Answer is: BApplying the weighted average rule,
Average cost of the mixture can be written as = [(16 x 2) + (21 x 3)]/(2 + 3)
Average cost of the mixture= 95/5 = Rs. 19
13. | | Average age of a family of four members is 20. What is the average age (in years) of the same family of four members after four years? | | (a)21 | | (b)24 | | (c)28 | | (d)36 |
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Answer is: BPresent average age of the family is 20 years.
After 4 years, each person in the family will be older by 4 years.
Hence, the average also increase by 4 years.
So, it is 24 years.
14. | | The average weight of a class of 40 students is 40 kg. If a new student, whose weight is 40 kg, joins the class, then what is the new average weight of the class? | | (a)40 kg | | (b)41 kg | | (c)44 kg | | (d)80 kg |
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Answer is: ATotal weight of the 40 students is 40 x 40 = 1600 kg
Total weight including the weight of the new student is 1600 + 40 = 1640 kg.
New total number of students is 41.
∴ The average weight of the class = 1640/41 = 40 kg.
15. | | The average age of two groups, with same number of persons in 30 and 40 years respectively. What is the average of the two groups together? | | (a)30 | | (b)35 | | (c)40 | | (d)CBD |
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Answer is: BLet the number persons in each group is X.
Total age of the first group = X x 30 = 30X
Total age of the second group = X x 40 = 40X
Average age of the two groups combined = (30X + 40X)/X + X
Average age of the two groups combined = 70/2 = 35 years.
16. | | In a company, the average height of female employees is 160 cm and the average height of male employees is 170 cm. If the total number of employees is 330, what is the average height of all the employees of the company? | | (a)160 cm | | (b)165 cm | | (c)170 cm | | (d)CBD |
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Answer is: DGiven the average height of female employees and that of male employees.
Also, given total number total number of employees.
But as we don't have the information regarding number of female employees or male employees, we cannot say any thing about the average height of all in employees.
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