1
Q:

# 8 years ago there were 5 members in the Arthur's family and then the average age of the family  was 36 years. Mean while Arthur got married and gave birth to a child. Still the average age of his family is same now. What is the age of his wife at the time of his child's birth was.If the difference between the age of her  child and herself was 26 years.

 A) 25 years B) 26 years C) 20 years D) can't be determined

Explanation:

Since we know that the difference b/w the age of any two persons remains always constant, while the ratio of their ages gets changed as the time changes.

so, if the age of his child be x (presently)

Then the age of  wife be x + 26 (presently)

Thus the total age = x + ( x + 26) = 32  [$\inline&space;\because$ 252-220 =32]

$\inline&space;\Rightarrow$ x = 3

$\inline&space;\therefore$ The age of her child is 3 years and her self  is 29 years. Hence her age at the time of the birth of her child was 26 years.

Q:

The average monthly salary of the employees of a firm is Rs.60 out of the employees 12 officers get an average of Rs.400 per month and the rest an average of Rs. 56 per month , Find the number of emp

Actual average salary of 12 officers = 400

$\inline&space;\fn_jvn&space;\therefore$ Total salary of 12 officers = 400 x 12 = 4800

Average of these 12  officers as a whole =60

Total salary of 12 officers as a whole = 60 x 12 = 720

The total salary of rest  = 4800 - 720 = 4080

Difference in average of the rest of officers  = 60 - 56 = 4

Rest of the officers = $\inline&space;\fn_jvn&space;\frac{4080}{4}=1020$

Total number of employees = 1020 + 12 = 1032

1215
Q:

The mean temperature of Monday to Wednesday was 37C and of Tuesday to Thursday was 34C . If the temperature on Thursday was (4/5) th that of Monday, the temperature on Thursday was?

$\inline&space;\fn_jvn&space;M+T+W&space;=(37\times&space;3)^{0}=111^{0}C$   -----------(1)

$\inline&space;\fn_jvn&space;T+W+Th=(34\times&space;3)^{0}=102^{0}C$

$\inline&space;\fn_jvn&space;\Rightarrow&space;T+W+\frac{4}{5}M&space;=&space;102^{0}C$                --------------(2)

(1) - (2) gives

$\inline&space;\fn_jvn&space;\frac{1}{5}$ th of temperature on Monday = $\inline \fn_jvn 111^{0}-102^{0}=9^{0}C$

$\inline&space;\fn_jvn&space;\Rightarrow$ Temperature on Monday = $\inline&space;\fn_jvn&space;45^{0}C$

$\inline&space;\fn_jvn&space;\therefore$ Temperature on Thursday = $\inline&space;\fn_jvn&space;\frac{4}{5}\times&space;45^{0}=36^{0}$

5005
Q:

A batsman makes a score of 87 runs in the 17th inning and thus increases his average by 3. Find his average after 17th inning?

Let the average after 7th inning = x

Then average after 16th inning = x - 3

$\inline&space;\fn_jvn&space;\therefore$ 16(x-3)+87 = 17x

$\inline&space;\fn_jvn&space;\therefore$  x = 87 - 48 = 39

8089
Q:

The average of 9 results is 50. The average of first four results is 52 and average of last four results is 49 . what is the fifth result?

Total of results = 50 x 9 = 450

Total of first four results = 52 x 4 = 208

Total of Last four results = 49 x 4 = 196

Hence the fifth result = 450 - (208 + 196) = 46

892
Q:

A man covers a journey from Meerut to Delhi by a car at an average speed of 40 km/hr. He returns back by scooter with an average speed 24 km/hr. Find his average speed during the whole journey?

Average speed = $\inline \fn_jvn \frac{2xy}{x+y}$ km/hr
=  $\inline \fn_jvn \frac{2\times 40\times 24}{40+24}=30$ km/hr