A box contains 5 red, 4 black and 4 blue balls. If 3 balls are drawn randomly from the box, what is the probability that there are exactly 2 blue balls in the three drawn balls ?

The simple interest on a sum of money will be ?1620 after six years. If the principal is increased by 100% after three years, what will the total interest be after six years ?

The difference between the simple interest and the compound interest compounded every six months at the rate of 30% per annum, at the end of l-~ years is ?5670. What is the sum ?

7 men and 11 boys can earn Rs. 10480 in 8 days. 8 men and 6 boys can earn Rs. 2840 in 12 days. In how many days will 12 men and 9 boys earn Rs. 25680 ?

If in the year 1993 the total number of boys appeared in the exam is 600, what is the difference between the percentage of boys passed and perecentage of girls passed ?

If in the year 1994 the total number of boys and the total number of girls appeared in the exam are equal to 800 each, what is the sum of the total number of boys and girls who passed that year ?

If in the year 1995 the total number of boys and the total number of girls appeared in the exam are 800 and 700 respectively, what is the ratio of the total number of boys passed to the total number of girls failed ?

If in the year 1998 the total number of boys and the total number girls appeared in the exam are 1250 and 850 respectively then the percentage of boys passed is what per cent of the percentage of girls failed ?