A brick measures 20 cm * 10 cm * 7.5 cm how many bricks will be required for a wall 25 m * 2 m * 0.75 m?

A. Rs. 31
B. Rs. 32.10
C. Rs. 40.40
D. Rs. 64.10
Explanation:
S.I. = (1000 * 10 * 4)/100 = Rs. 400
C.I. = [1000 * (1 + 10/100)4 – 1000] = Rs. 464.10 Difference = (464.10 – 400) = Rs. 64.10

A. Rs.2520
B. Rs.3120
C. Rs.3320
D. Rs.2760
E. None of these
Explanation:
Let A be the amount received at the end of the three years.
A = 4800[1 + 10/100][1 + 20/100][1 + 25/100]
A = (4800 * 11 * 6 * 5)/(10 * 5 * 4)
A = Rs.7920
So the interest = 7920 – 4800 = Rs.3120