CBSE Class 7 Answered

1. what is the percentage in each of the following?

a. 825m of 75km b. 225 mins. of 2 hours

2. find a number whose

(i) 8% is 16 (ii) 6 1/4% is 4

3. the population of a city decreased by 5% due to earthquake. if now it is 1,90,000 what was the population before earthquake?

4.a lady sold 40 sarees at a profit of 20%. if the cost of one saree is rs. 100, find the selling price of each saree.

5. if 15:x =60% then what is the value of x?

6. Harish bought a second hand printer for rs. 1200 and spent rs.200 on its repairs. he sold it for rs. 1680. find his profit or loss percent.

7. how long will it take for rs. 2500 invested at the rate of 8% per annum simple interest to amount to rs. 3100?

8. What is the interest on rs. 12000 at 6% per annum for 146 days?

9. A student has to score 35% marks to pass an exam. Anjali scored 154 marks and failed by 21 marks. Find the maximum marks.

10. A dealer bought for watch for rs. 420. find the selling price if it is sold:

(i)AT a gain of 5% (ii) at a loss of 5%

11. in a election between 2 candidates A and B , 30,000 votes were polled. A won the election with a margin of 400 votes. Find the ratio of votes polled in favour of each candidate.

12. Lata spent 20% of the money she had on jeans and 5% on a pair of slippers. she was left with rs. 2700. how much money did she have int the beginning?

13. Bindun wants to invest rs. 10,000 in a bank. which of the following banks will be a better option for her to invest the money?

Bank 1: rs. 15,000 invested in this bank amount to rs. 20,175 in 3 years.

Bank 2: rs. 24,000 invested in this bank amount to rs. 34,720 in 4 years

Asked by omsingh | 11 Jul, 2015, 03:37: PM

Expert Answer

1. space left parenthesis a right parenthesis space W e space k n o w space t h a t space 1 space k m equals 1000 space m therefore 75 space k m equals 75 cross times 1000 m space space space space space space space space space space space space space equals 75000 space m T h u s comma space p e r c e n t a g e space o f space t h e space r a t i o space 825 space m space o f space 75 space k m equals 825 over 75000 cross times 100 equals 1.1 % left parenthesis b right parenthesis space W e space k n o w space t h a t space 1 space h o u r equals 60 space m i n s. therefore 2 space h o u r s equals 2 cross times 60 equals 120 space m i n s T h u s comma space p e r c e n t a g e space o f space t h e space r a t i o space 225 space m i n s space o f space 2 space h o u r s equals 225 over 120 cross times 100 equals 187.5 % 2. space left parenthesis i right parenthesis L e t space apostrophe x apostrophe space b e space t h e space n u m b e r space w h o s e space 8 % space i s space 16. T h u s comma space 8 % space o f space x space equals 16 therefore 8 over 100 cross times x equals 16 M u l t i l y space 100 over 8 space t o space b o t h space t h e space s i d e s comma space w e space h a v e comma 100 over 8 cross times 8 over 100 cross times x equals 100 over 8 cross times 16 therefore 1 cross times x equals fraction numerator 100 over denominator up diagonal strike 8 end fraction cross times up diagonal strike 16 squared end strike therefore x equals 200 T h e r e f o r e comma space 8 % space o f space 200 space i s space 16 left parenthesis i i right parenthesis L e t space apostrophe x apostrophe space b e space t h e space n u m b e r space w h o s e space 6 1 fourth % space i s space 4. T h u s comma space 6 1 fourth % space o f space x space equals 4 therefore 25 over 4 % space o f space x equals 4 therefore fraction numerator 25 over denominator 4 cross times 100 end fraction cross times x equals 4 M u l t i l y space 400 over 25 space t o space b o t h space t h e space s i d e s comma space w e space h a v e comma 400 over 25 cross times 25 over 400 cross times x equals 400 over 25 cross times 4 therefore 1 cross times x equals 400 over 25 cross times 4 therefore x equals 64 T h u s comma space 6 1 fourth % space o f space 64 space i s space 4 3. L e t space P space b e space t h e space p o p u l a t i o n space b e f o r e space t h e space e a r t h q u a k e. N u m b e r space o f space p e o p l e space d i e d space d u e space t o space e a r t h space q u a k e equals 5 % space o f space P P r e s e n t space p o p u l a t i o n equals P o p u l a t i o n space b e f o r e space t h e space e a r t h q u a k e minus N u m b e r space o f space p e o p l e space d i e d space d u e space t o space e a r t h space q u a k e G i v e n space t h a t space P r e s e n t space p o p u l a t i o n equals 1 comma 90 comma 000 T h u s comma space w e space h a v e comma 190000 equals P minus 5 % space o f space P therefore P minus 5 over 100 P equals 190000 therefore P open parentheses 1 minus 5 over 100 close parentheses equals 190000 therefore P open parentheses fraction numerator 100 minus 5 over denominator 100 end fraction close parentheses equals 190000 therefore P open parentheses 95 over 100 close parentheses equals 190000 M u l t i p l y space b o t h space t h e space s i d e s space o f space t h e space a b o v e space e q u a t i o n space b y space 100 over 95 comma space w e space h a v e comma P open parentheses 95 over 100 close parentheses cross times 100 over 95 equals 190000 cross times 100 over 95 therefore P cross times 1 equals 190000 cross times 100 over 95 therefore P equals 190000 cross times 100 over 95 therefore P equals 200000 T h e r f o r e comma space t h e space o r i g i n a l space p o p u l a t i o n space b e f o r e space t h e space e a r t h space q u a k e space i s space 200000.

Answered by Vimala Ramamurthy | 12 Jul, 2015, 09:33: AM

CBSE Class 7 Answered

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