21.

Successive discounts of 10%, 20% and 50% will be equivalent to a single discount of

• 36%

• 64%

• 80%

• 80%

A retailer offers the following discount schemes for buyers on an article.
I.   Two successive discounts of 10%
II.  A discount of 12% followed by a discount of 8%.
III. Successive discounts of 15% and 5%
IV. A discount of 20%.
The selling price will be minimum under the scheme.

• I

• II

• III

• III

A mixture contains 80% acid and rest water. Part of the mixture that should be removed and replaced by same amount of water to make the ratio of acid and water 4 : 3 is

An employer reduces the number of his employees in the ratio 9 : 8 and increases their wages in the ratio 14 : 15. If the original wage bill was ₹ 18,900, find the ratio in which the wage bill is decreased.

• 20 : 21

• 21 : 20

• 20 : 19

• 20 : 19

The batting average for 40 innings of a cricketer is 50 runs. His highest score exceeds his lowest score by 172 runs. If these two innings are excluded, the average of the remaining 38 innings is 48 runs. The highest score of the player is

• 165

• 170

• 172

• 172

A and B are two alloys of gold and copper prepared by mixing metals in the ratio 7 : 2 and 7 : 11 respectively. If equal quantities of the alloys are melted to form a third alloy C, the ratio of gold and copper in C wil be

• 5 : 7

• 5 : 9

• 7 : 5

• 7 : 5

In a laboratory, two bottles contain mixture of acid and water in the ratio 2 : 5 in the first bottle and 7 : 3 in the second. The ratio in which the contents of these two bottles be mixed such that the new mixture has acid and water in the ratio 2 : 3 is

• 4 : 15

• 9 : 8

• 21 : 8

• 21 : 8

The average of three numbers is 154. The first number is twice the second and the second number is twice the third. The first number is

• 264

• 132

• 88

• 88

The average salary of all the staff in an office of a corporate house is ₹ 5,000. The average salary of the officers is ₹ 14,000 and that of the rest is ₹ 4,000. If the total number of staff is 500, the number of officers is 

• 10

• 15

• 25

• 25

The average marks of 40 students in an English exam is 72. Later it is found that three marks 64, 62 and 84 were wrongly entered as 68, 65 and 73. The average after mistakes were rectified is

• 70

• 72

• 71.9

• 71.9