In a triangle ABC, right-angled at C, if \(sec A={13\over5}\), then find the value of \(\frac{1+ \sin A}{\cos B}\).

A student takes 1.25 hours to travel from home to school at a speed of 4 km/h. By what percentage should he increase his speed to reduce the time by 25% to cover the same distance from school to home?

If \({sin^2\theta\over tan^2\theta-sin^2\theta}=5\), then the value of \(\frac{24\cos^2\theta-15\sec^2\theta}{6\ \rm cosec^2 \theta-7\cot^2\theta}\) is:

Ramesh deposited Rs. 15600 in a fixed deposit at the rate of 10% per annum simple interest. After every second year, he adds his interest earnings to the principal. The total interest at the end of fourth year is