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Q:

In a village the average age of n people is 42 years. But after the verification it was found that the age of a person had been  considered 20 years less than the actual age, so the new average, after the correction,increased by 1. The value of n is :

A) 21 B) 20
C) 22 D) None of these

Answer:   B) 20

Explanation:

It is the same as a person with 20 years more age  replaces an existing person of the group ( or village)

Since the total age of the village having n persons, is being increased by 20 years and the average age of village is being increased by 1 year, hence there are total 20 people in the village.

 

Alternatively :  ( n x 42 ) + 20 = ( n x 43 )

                          => n=20

Q:

There are 100 students in 3 sections A, B and C of a class. The average marks of all the three sections was 84. The average of B and C was 87.5 and the average marks of students in A section was :

A) 20 B) 35
C) 54 D) 40
 
Answer & Explanation Answer: A) 20

Explanation:

Numbers of students in section A = x
∴ Numbers of students in section B and C = (100 – x)
∴ x 70 + (100 – x) 87.5 = 84 100
=> 70x + 87.5 100 – 87.5x = 8400
=> 8750 – 17.5x = 8400
=> 17.5x = 8750 – 8400 => x = 20.

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4 41
Q:

The average monthly salary of 24 employees in an organisation is Rs. 1500. If the manager's salary is added, then the average salary increases by Rs. 400. What is the manager's monthly salary ?

A) Rs. 8840 B) Rs. 11,500
C) Rs. 12,800 D) Rs. 9450
 
Answer & Explanation Answer: B) Rs. 11,500

Explanation:

Manager's monthly salary

= Rs. (1900 x 25 - 1500 x 24) = Rs. 11,500

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2 54
Q:

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 ?

A) 34 B) 36
C) 38 D) 40
 
Answer & Explanation Answer: A) 34

Explanation:

M + Tu + W + Th = 4 x 48 = 192
Tu + W + Th + F = 4 x 46 = 184
M = 42
Tu + W + Th = 192 - 42 = 150
F = 184 – 150 = 34

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1 70
Q:

A batsman in his 17th innings makes a score of 85 and their by increasing his average by 3. What is his average after the 17th innings ?

A) 34 B) 36
C) 35 D) 37
 
Answer & Explanation Answer: D) 37

Explanation:

16x + 85 = 17(x + 3)

x = 34 + 3 = 37

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2 90
Q:

What will be the cost of building a fence around a square plot with area equal to 289 sq ft, if the price per foot of building the fence is Rs. 58 ?

A) Rs. 3748 B) Rs. 3847
C) Rs. 3944 D) Rs. 3154
 
Answer & Explanation Answer: C) Rs. 3944

Explanation:

Let the side of the square plot be 'a' ft.
Given area of the plot (a x a) = 289 => a = 17
Length of the fence = Perimeter of the plot = 4a = 68 ft.
Cost of building the fence = 68 x 58 = Rs. 3944.

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3 79