3
Q:

The average expenditure of the hotel when there are 10 guests is Rs. 60 per guests and the average expenditure is Rs.40 when there are 20 Guests. If it is known that there are some fixed expenses irrespective of the number of guests then the average expenditure per guest  whe there are 40 guests in the hotel.

A) Rs. 30 B) Rs. 25
C) Rs. 20 D) can't be determined

Answer:   A) Rs. 30



Explanation:

Let the fixed expenditure of the hotel be Rs.x and the variable expenditure ( which is dependent on the guest ) is Rs.y , then

                   x + 10y = 600        ---------(1)

                   x + 20y = 800       ----------(2)

\inline \Rightarrow              10y = 200

           y = Rs. 20   and    x= 400

Hence the total expenditure when there are 40 guests = 400 + 40 x 20 = 1200

\inline \therefore average expenditure = \inline \frac{1200}{40} = Rs. 30

Q:

The mean of 100 observations is 40. It is found that an observation 84 was misread as 48. Then the correct mean is ?

A) 40.36 B) 41.24
C) 41.92 D) 42.05
 
Answer & Explanation Answer: A) 40.36

Explanation:

Given,

mean of 100 observations is 40

=> Total of 100 observations = 40 x 100 = 4000

84 is misread as 48

=> Difference = 84 - 48 = 36

=> Now, new total of 100 observations = 4000 + 36 = 4036

Correct Mean = 4036/100 = 40.36

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7 231
Q:

The average marks of a student in 7 subjects is 85. His average marks in 6 subjects except English is 83. What is his marks in English ?

A) 97 B) 98
C) 92 D) 93
 
Answer & Explanation Answer: A) 97

Explanation:

Marks in English  = 85×7 – 83×6

= 595 – 498

= 97

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11 404
Q:

Navaneet has thrice the money Poonam has and Poonam has 25% more money than Hebah. If the average money of the three is Rs. 350, What is the amount that Navaneet has ?

A) Rs. 175 B) Rs. 220.75
C) Rs. 218.55 D) Rs. 656.25
 
Answer & Explanation Answer: D) Rs. 656.25

Explanation:

Assume Hebah has Rs. M

Since 25% more money at Poonam

=> Money at Poonam = M + (25% of M)

=> Money at Poonam = M + 0.25M = Rs. 1.25M

Money with Navaneet is thrice the money with Poonam,

=> Money at Navaneet = 3(1.25M) = Rs. 3.75M

Now, sum of all Money = (M + 1.25M + 3.75M) = Rs. 6M

But given the average of the money is Rs. 350

=> 6M/3 = 350

=> 2M = 350

=> M = 350/2 = Rs. 175

=> Amount of money Navaneet has = Rs. 3.75M = 3.75 x 175 = Rs. 656.25.

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6 409
Q:

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 ?

A) 56 B) 64
C) 87 D) 78
 
Answer & Explanation Answer: D) 78

Explanation:

Using Trial and error method,

we get the number of girls in the hall = 78

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13 787
Q:

The average age of 7 boys is increased by 1 year when one of tem whose age is replaced by a girl. What is the age of the girl ?

A) 33 yrs B) 27 yrs
C) 21 yrs D) 29 yrs
 
Answer & Explanation Answer: D) 29 yrs

Explanation:

Let the avg age of 7 boys be 'p' years
Let the age of the girl be 'q' years
From given data,
The age of 7 boys = 7p years
Now the new average = (p + 1) when 22 yrs is replaced by q
Now the age of all 7 will become = 7(p + 1) yrs
Hence, 7p - 22 + q = 7(p + 1) yrs
7p - 22 + q = 7p + 7
q = 22 + 7 = 29

Therefore, the age of girl = q = 29 years.

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