RS Aggarwal Class 7 Math Tenth Chapter Percentage Exercise 10B Solution

RS Aggarwal Class 7 Math Tenth Chapter Percentage Exercise 10B Solution

EXERCISE 10B

(1) Rupesh secures 495 marks out of 750 in his annual examination. Find the percentage of marks obtained by him.

(2) The monthly salary of a typist is Rs 15625. If he gets an increase of 12%, find his new salary.

(3) The excise duty on a certain item has been reduced to Rs 760 from Rs 950. Find the reduction per cent in the excise duty on that item.

(4) 96% of the cost of a TV is Rs 10464. What is its total cost?

(5) 70% of the students in a school are boys and the number of girls is 504. Find the number of boys in the school.

Solution: Let the total number of student be x.

Percentage of boys = 70%

∴ Percentage of girls = (100 – 70)% = 30%

(6) An ore contains 12% copper. How many kilograms of the ore are required to get 69 kg of copper?

(7) 36% of the maximum marks is required to pass a test. A student gets 123 marks and is declared fail by 39 marks. Find the maximum marks.

(8) A fruit-seller had some apples. He sells 40% of them and still has 420 apples. Find the number of apples he had originally.

Solution: Let the required number of apples be x.

The percentage of sells apple = 40%

The percentage of rest apple = (100 – 40) = 60%

(9) In an examination, 72% of total examinees passed. If the number of failures is 392, find the total number of examines.

Solution: Let the total number of examines be x.

The percentage of passed examines = 72%

The percentage of failed examines = (100 – 72) = 28%

(10) After deducting a commission of 5%, a moped costs Rs 15200. What is its gross value?

Solution: Let the grass value be x.

Percentage of deducting commission = 5%

Percentage of mode commission = (100 – 5) = 95%

(11) Gunpowder contains 75% of nitre and 10% sulphur, and the rest of it is charcoal. Find the amount of charcoal in 8 kg of gunpowder.

Solution: Total amount of gunpowder = 8 kg = 8000 g

(12) Chalk contains 3% of carbon, 10% of calcium and 12% of oxygen. Find the amount in grams of each of these substances in 1 kg of chalk.

(13) Sonal went to school for 219 days in full year. If her attendance is 75%, find the number of days on which the school was open.

Solution:  Let the number of days which the school was open be x.

(14) 3% commission on the sale of a property amounts to Rs 42660. What is the total value of the property?

Solution: Let the total value of property be x.

(15) In an election, there were two candidates A and B. The total number of voters in this constituency was 60000 and 80% of the total votes were polled. If 60% of the polled votes were cast in favour of Ahow many votes were received by B?

(16) The price of a shirt is reduce by 12% in a discount sale. If its increased price is Rs 1188, find its original price.

(17) The price of a sweater is increased by 8%. If its increased price is Rs 1566, find the original price.

(18) After spending 80% of his income and giving 10% of the remainder in a charity, a man has Rs 46260 left with him. Find his income.

(19) A number is increased by 20% and increased number is decreased by 20%. Find the net increase or decrease per cent.

(20) The salary of an officer is increased by 20%. By what percentage should the new salary be reduce to restore the original salary?

(21) A property dealer charges commission at the rate 2% on the first Rs 2000000, 1% on the next Rs 200000 and 0.5% on the remaining price. Find his commission on the property that has been sold for Rs 540000.

(22) Nikhil’s income is 20% less than of Akhil. How much per cent is Akhil’s income more than that of Nikhil’s?

(23) John’s income is 20% more than that of Mr Thomas. How much per cent is the income of Mr Thomas less than that of Jhon?

(24) The value of a car decreases annually by 20%. If the present value is Rs 387000, what was its value 1 year ago?

(25) The value of car decreases annually by 20%. If the present value of the car be Rs 450000, what will be its value after 2 years?

(26) The population of a town increases 10% annually. If its present population is 60000, what will be population after 2 years?

(27) Due to an increase in the price of sugar by 25%, by how much per cent must a householder decrease the consumption of sugar so that there is no increase in the expenditure on sugar?

Solution: Let the earlier consumption of sugar be 100 grams and let its price be Rs 100.