A library has an average of 510 visitors on Sundays and 240 on other days. The a

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Question
A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is :
Options
A. 285
B. 290
C. 297
D. 305

Correct Answer

285

Explanation

Since the month begins with a Sunday, so there will be five Sundays in the month,

Required average = (510 * 5 + 240 * 25) / 30 = 8550/30 = 285.

Average problems

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1. A student was asked to find the arithmetic mean of the numbers 3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and x. He found the mean to be 12. What should be the number in place of x ?
Options
A. 6
B. 7
C. 8
D. 9

Discuss

2. The average temperature for Monday, Tuesday, Wednesday and Thursday was 48 degrees and for Tuesday, Wednesday, Thursday and Friday was 46 degrees. If the temperature on Monday was 42 degrees. Find the temperature on Friday ?
Options
A. 34
B. 36
C. 38
D. 40

Discuss

3. The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years, The ratio of the number of boys to the number of girls in the class is :
Options
A. 1 : 2
B. 2 : 3
C. 3 : 4
D. 4 : 5

Discuss

4. A certain factory employed 600 men and 400 women and the average wager was Rs. 25.50 per day, If a woman got Rs. 5 less than a man, then what are their daily wages ?
Options
A. m:25.50 w:27.50
B. m:27.50 w:22.50
C. m:26.50 w:27.50
D. m: 24.50 w:26.50

Discuss

5. If the arithmetic mean of seventy-five numbers is calculated, it is 35. if each number is increased by 5, then mean of new numbers is :
Options
A. 30
B. 40
C. 50
D. 60

Discuss

Correct Answer: 40

Explanation:

Let the numbers are $x_{1,} x_{2,} . . . . . . . x_{75}$

By Hypothesis , $\frac{x_{1} + x_{2} + . . . . x_{75}}{75} = 35$ ......(i)

Mean of new numbers = $\frac{(x_{1} + 5) + (x_{2} + 5) + . . . . . . . (x_{75} + 5)}{75}$

$\frac{x_{1} + x_{2} + . . . . . . x_{75} + 5 * 75}{75}$

$\frac{x_{1} + x_{2} + . . . . . . x_{75}}{75} + \frac{375}{75} = 35 + 5 = 40$ By (i)

6. A car owner buys petrol at Rs 7.50, Rs. 8 and Rs. 8.50 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Rs. 4000 each year ?
Options
A. 6.23
B. 7.98
C. 8.97
D. 9.89

Discuss

7. The average weight of 45 passengers in a bus is 52 kg. 5 of them whose average weight is 48 kg leave the bus and other 5 passengers whose average weight is 54 kg join the bus at the same stop. What is the new average weight of the bus?
Options
A. 54.21 kgs
B. 51.07 kgs
C. 52.66 kgs
D. 53.45 kgs

Discuss

8. 19 friends went to a restaurant for a combined weekend dinner party. 13 of them spent Rs. 79 each on their dinner and the rest spent Rs. 4 more than the average expenditure of all the 19. What was the total money spent by them?
Options
A. Rs. 1398.96
B. Rs. 1457.09
C. Rs. 1662.35
D. Rs. 1536.07

Discuss

9. If the average height of boys in a hall is 180 cm and that of girls is 150 cm. If the average height of the gathering is 165 cm, then find the number of girls present in the hall if the number of boys present in the hall are 78 ?
Options
A. 56
B. 64
C. 87
D. 78

Discuss

10. If the mean of a, b, c is M and ab + bc + ca = 0, then the mean of a2+b2+c23 is :
Options
A. M
B. 3 M^2
C. 2 (M/3)
D. M^2

Discuss

Correct Answer: 3 M^2

Explanation:

We have : ( a + b + c) / 3 = M or (a + b + c) = 3M.

Now. ${(a + b + c)}^{2} = {(3 M)}^{2} = 9 M^{2}$ .

$< = > a^{2} + b^{2} + c^{2} + 2 (a b + b c + c a) = 9 M^{2}$

$a^{2} + b^{2} + c^{2} = 9 M^{2}, (a b + b c + c a = 0)$

Required mean = $(\frac{a^{2} + b^{2} + c^{2}}{3}) = \frac{9 M^{2}}{3} = 3 M^{2}$ .

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A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is :

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A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is :

Average problems

Search Results

More in Aptitude:

Aptitude

Engineering

Programming

Reasoning

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