2
Q:

# 123 typists typeed 984 papers in 1/15 hour. The number of papers typed for  minute by a average typist is:

 A) 1 B) 2 C) 3 D) 5

Explanation:

Use unitary method:

In $\inline&space;\frac{1}{15}$ hours, 123 typists can type 984 paper

In 1 minute, 123 typists can type  $\inline&space;\frac{984}{4}$ = 246 papers

In 1 minute, 1 typist can type $\inline&space;\frac{246}{123}$ =2 papers      [ Hint $\inline&space;\frac{1}{15}$ hours = 4 minutes]

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

Explanation:

Given,

mean of 100 observations is 40

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

=> Difference = 84 - 48 = 36

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

Correct Mean = 4036/100 = 40.36

7 240
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

Explanation:

Marks in English  = 85×7 – 83×6

= 595 – 498

= 97

11 410
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

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.

6 423
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

Explanation:

Using Trial and error method,

we get the number of girls in the hall = 78

13 799
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

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.