The average revenues of 7 consecutive years of a company is Rs 83 lakhs. If the average of first 4 years is Rs 78 lakhs and that of last 4 years is Rs 90 lakhs, find the revenue for the 4th year.
If the amount received at the end of 2nd and 3rd year at Compound Interest on a certain Principal is Rs 22472, and Rs 23820.32 respectively, what is the rate of interest?