Quantitative Aptitude - Arithmetic Ability Questions

Let the principle amount be Rs. P

Interest rate = 12%

Total amount he paid after 5 years = Rs. 1280

ATQ, 

$$\begin{gathered} P + I = PTR100 + P \\ 1280 = PTR100 + 1 \\ 1280 = P5 x 12100 + 1 \\ 16P10 = 1280 \\ P = 80 x 10 = 800 \end{gathered}$$

Hence, the amount he borrowed = P = Rs. 800.

Let the price of 1 litre of diesel be Rs.x and let Karthik initially buy 'y' litres of diesel.
Therefore, he would have spent Rs. xy on diesel.

When the price of diesel increases by 25%, the new price per litre of diesel is 1.25x.

Karthik intends to increase the amount he spends on diesel by 15%.
i.e., he is willing to spend xy + 15% of xy = 1.15xy

Let the new quantity of diesel that he can get be 'q'.
Then, 1.25x x q = 1.15xy
Or q = (1.15/1.25)y = 0.92y.

As the new quantity that he can buy is 0.92y, he gets 0.08y lesser than what he used to get earlier.

Or a reduction of 8%.

1 2 3 4 5 6(Shankar) 7(Nitu) 8(Althaf) 9 10 11 12 13 14
Here, Althaf is 8th from front, Shankar is 9th from rear end and Nitu is between them
So minimum no. of boys standing in the queue = 14

Here 40% of 80 is given as

40100 x 80 = 8 x 4 = 32

 Since 8 does not occur in 1000, we have to count the number of times 8 occurs when we list the integers from 1 to 999. Any number between 1 and 999 is of the form xyz, where 0≤x,y,z≤9.

Let us first count the numbers in which 8 occurs exactly once.

Since 8 can occur atone place in 3C1ways. There are 3 x 9 x 9 such numbers.

Next, 8 can occur in exactly two places in 3C2×9 such numbers. Lastly, 8 can occur in all three digits in one number only.

Hence, the number of times 8 occur is 

 1×3×92+2×3×9+3×1 = 300