Question

how to solve this type of question ,please tell me...


The average of six numbers is 30.If the average of first four is 25 and that of last three is 35, the fourth number is :

A) 25

B) 30

C)35

D)40

5. The average age of 30 students is 9 years .If the age of their teacher is included ,it becomes 10 years . The age of the teacher (in years ) is :

A) 27

B) 31

C) 35

D) 40

6. After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago.what is the difference between the ages of the replaced and the new member ?

A) 15 yrs

B) 8 yrs

C) 4 yrs

D) 2 yrs

ans A

7. Three years ago , the average age of A, B and C was 27 years and that of B and C, 5 years ago was 20 years. A’s present age is :

A) 30 yrs

B) 35 yrs

C) 40 yrs

D)48 yrs

8. three years ago, the average age of a family of 5 members was 17 years. A baby having been born , the average age of the family is the same today. The present age of the baby is :

A) 2 yrs

B) 2.4 yrs

C) 3 yrs

D)1.5 yrs

9. The average weight of 6 men decreases by 3 kg when one of them weighing 80 kg is replaced by a new man . The weight of the new man is :

A) 56kg

B)58 kg

C)62 kg

D) 76 kg

10. The average of ten numbers is 7 .If each number is multiplied by 12 , then the average of new set of numbers is :

a) 7

B) 19

C) 82

d) 84

11. A batsman makes a score of 87 runs in the 17th inning and thus increases his average by 3 . Find his average after 17th inning.

A) 39 B) 38 C) 38.5 D) 39.5

12. Out of four numbers ,the average of first three is 16 and that of the last three is 15 .If the last number is 18,the first number is :

A) 20

B) 21

C) 23

D) 25

13. Narasimha,Madhu and pavan started a business by investing

Rs. 1, 20,000, Rs. 1, 35,000 and Rs 1, 50,000 respectively. Find the

share of Pavan, out of an annual profit of Rs 56,700.

A) Rs .16, 800

B) Rs.18, 900

C) Rs.21, 000

D) none

14. Anand and Deepak started a business investing Rs. 22,500 and Rs.35, 000 respectively. Out of a total profit of Rs. 13,800, Deepak’s share is_______.

A) Rs .5400

B) Rs. 7200

C) Rs. 84,000

D) 94,000

15. A starts business with Rs. 35,000 and after 5 months, B joins with A as his partner. After a year, the profit is divided in the ratio 2:3. What is B’s contribution in the capital?

A) Rs .7500

B) Rs. 8000

C) Rs. 8500

D) Rs. 9000

16. A and B are partners in a business. A contributes 1/4 of the capital for 15 months and B received 2/3 of the profit .For how long B’s money was used.

A) 6 months B) 9 months C) 10 months D) 1 year

17. X and Y invested in a business. They earned the profit, which they divided in the ratio of 2:3. If X invested Rs. 40,000, the amount invested by Y is

A) Rs .60, 000

B) Rs. 8000

C) Rs. 50,000

D) Rs. 90,000

18. A, B and C enter into a partnership and their shares are in the ratio 1/2:1/3:1/4.After 2 months, A withdraws half of his capital and after 10 months, a profit of Rs. 378 is divided among them. What is B’s share?

A) Rs .129

B) Rs. 144

C) Rs. 156

D) Rs. 168

19. A, B, C enters into a partnership investing Rs 35000 Rs 45000 and Rs 55000 respectively. The respective shares of A, B and C in annual profit of Rs 40,500 are

A) Rs.10, 500 Rs.13, 500 Rs.16, 500

B) Rs.11, 500 Rs.13, 000Rs.16, 000

C) Rs.11, 000 Rs.14, 000 Rs.15, 500

D) Rs.11, 500 Rs.12, 500 Rs16,500

20. 2 is what percent of 50?

A)2%

B)10%

C)100%

D)4%

21. 5% of (25% of Rs1600) is

A)Rs. 5

B)Rs 17.50

C) Rs 20

D)Rs 25

22. In an examination, 35% of the students passed and 455 failed. How many students appeared for the examination?

A) 490

B) 700

C) 845

D) 1300

23. At an election a candidate who gets 84% of the votes is elected by a majority of 476

Votes what is the total number of votes polled?

A) 672

B) 700

C) 749

D) 848

24.1100 boys and 700 girls are examined in a test; 42% of the boys and 30% of thegirlsPass.The percentage of the total who failed is:

A) 58%

B) 62 2/3%

C) 64%

D) 78%

25. Find S.P when C.P= Rs 56.25,gain=20%.

A) 68.34

B) 67.50

C) 61.25

D) 66.66

Answer 1

40 is correct there in its question

Answer 2

4th number is 25

ie:  sum of  elements= average * number of elements

     sum of  6 elements =6*30=180

     sum of  first 4 elements = 4*25 =100

     sum of last 3  elements =3* 35 =105

    4th number is =      (sum of  first 4 elements + sum of last 3  elements) -    sum of  6 elements

                              =(100+105)-180

                               =205-180

                               =25