A sum of money becomes 4 times at simple interest in 10 years. What is the rate of interest?

If a clock strikes 12 in 33 seconds, it will strike 6 in how many seconds?

What approximate value will come in place of the question mark (?) in the following questions?

175 x 28 + 275 x 27.98 =? 

The Ratio of the employees in company A to B is 6: 5 and the number of employees in C to A is 13: 10. If the ratio of the number of male to female employees in A, B and C is 7: 5, 2: 3 and 7: 6 respectively, then the number of female employees in all the companies together is approximately what percent of the total number of employees in all the companies together?

There are 45 male and 15 female employees in an office. If the mean salary of the 60 employees is Rs 4800 and the mean salary of the male employees is Rs 5000, then the mean salary of the female employees is

There is 40 % increase in an amount in 8 years at simple interest. What will be the compound interest  (in rupees) of Rs 30000 after 2 years at the same rate? 

The length, breadth and height of a hall are 144 m, 180 m and 384 m respectively. The length of the longest scale that can measure the three dimensions of the hall exactly is: