3
Q:

# The average of any 5 consecutive odd natural numbers is k . If two more such numbers , just next to the previous 5 numbers are added , the new average becomes

 A) 2(k+1) B) 2k-3 C) 2k+1 D) k+2

Explanation:

The 5 consecutive odd numbers whose average is k are  (k-4), (k-2), k, (k+2), (k+4)

Again the average of (k-4), (k-2), k, (k+2), (k+4), (k+6), (k+8) is (k+2)

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

5003
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

8078
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