The average marks obtained by Raghav in 12 tests is 24. Zubeida has maintained an average of 23 so far but has taken only 9 of the tests. If each test is out of 30, at least how much Zubeida score in any one of the remaining three tests to still have a chance to match Raghav's performance?
If the time increases by 7 years, then simple interest increases by Rs 8400 on a sum of Rs 6000. What is the rate (in percentage) of interest per annum?