at what rate of interest per annum,the amount of 10000 will be doubled in 5 years,interest being compounded quarterly

Answer 1

let the quarterly rate be j
1000(1+j)^20 = 2000
(1+j)^20 = 2
1+j = 2^(1/20) = 1.035265
j = .035265

the annual rate compounded quarterly is .14106
= 14.1 %

(good luck finding that these days)

Answer 2

no problem. go to any bookie or loan shark!