If a 7-storey building has a 28 m long shadow, the number of storeys of the building whose shadow is 48 m long is:

10 women take 16 days to complete a work which can be completed by 6 men in 8 days. 12 men started working and after 2 days 6 men left, and 5 women joined them. In how many days will the work be completed?

What is the present worth of Rs. 1,100 due in 2 years at 5% simple interest per annum?

If $\rm cos x + sec x = {7 \over2 \sqrt3}$, then the value of cos²x + sec²x will be ________.