A student multiplies a number by 5/3 instead of 3/5. What is the percentage error in the calculation?

The price of an article is reduced by 25% but the daily sale of the article is increased by 30%. The net effect on the daily sale receipts is

A reduction of 20% in the price of rice enables a man to buy 5 kg more for Rs.100. The price of the rice before reduction was-

60% boys are failed in History and 65% boys are failed in Geography while total 30% boys are failed in both the subjects. If total 1200 boys appeared in the examination then total how many boys are passed?

A man gives 20% of his money to his eldest son, 30% of remaining he gives to his younger son. 10% of the remaining he gives in a school for poor boys still he has Rs.100.80. Find his total sum. 

If the length of a rectangle increases by 50% and the breadth decreases by 25%, then what will be the percent increase in its area?

The rate of wheat increased by 25%. How many percent may the use of wheat be reduced so that the expenditure on that item remains the same?

With the increase in the price of sugar by 45%, a consumer can buy 9 kg less sugar for Rs. 1740. What is the increased price per kg of sugar?