Two trains 128 meters and 122 meters long are running towards each other on parallel lines at 48 kmph and 42 kmph respectively. In what time will they clear off each other from the moment they meet?

Rs. 2,000 is invested at 10% p.a. on simple interest. If that interest is added to the principal after every 20 years, the amount will become Rs. 14,000 after

The speed of a  boat in still water is 20 kmph and the rate of current is 4 kmph. The distance travelled by the boat downstream in 30 minute is

Rohit starts a business with Rs.6,500 and after 8 months Shyam joins Rohit as his partner. After 4 years the profit is divided in the ratio of 13 : 12. What is Shyam’s contribution in the capital?

Direction: what should come in place at question mark(?).

$$ {4\over 7}×{2{4\over 5}÷{2\over 5}=?}$$

Direction: what should come in place at question mark(?).

(0.85% of 405) +(2.25% of 550)=?

Direction: what should come in place at question mark(?).

$$ {1\over 8}×(223+?)=71$$

Direction: what should come in place at question mark(?).

$$ {\sqrt{4489}+(71)^{2}-(?)^{2}=2707}$$