SOLVED PAPER 2020 (CDS) (II) (Elementary Mathematics)

Total Questions: 100

21. A shopkeeper sells his articles at their cost price but uses a faulty balance which reads 1000 gm for 800 gm. What is the actual profit percentage?

Correct Answer: (b) 25%
Solution:

22. A river 3 m deep and 40 m wide is flowing at the rate of 2 km/h and falls into the sea. What is the amount of water in litres that will fall into the sea from this river in a minute?

Correct Answer: (a) 4000000 L
Solution:Speed of flow of water = 2 km/h

23. If a television set is sold at ₹ x, a loss of 28% would be incurred. If it is sold at ₹ y, a profit of 12% would be incurred. What is the ratio of y to x ?

Correct Answer: (d) 14 : 9
Solution:Let the cost of television be ₹ 100.

24. By increasing the speed of his car by 15km / h a person covers a distance of 300 km by taking an hour less than before. What was the original speed of the car ?

Correct Answer: (c) 60 km/h
Solution:Let the speed of car = x km/h

25. Three persons start a business ⅓ : ¼ : ⅕ with capitals in the ratio The first person withdraws half his capital after 4 months. What is his share of profit if the business fetches an annual profit of ₹ 96800 ?

Correct Answer: (a) ₹ 32000
Solution:Three person start a business with capital in the ratio,

26. If x varies as y, then which of the following is/are correct?

Correct Answer: (b) 2 and 3
Solution:Given x varies as y,

27. Ena was born 4 year after her parents marriage. Her mother is 3 year younger than her father and 24 year older than Ena, who is 13 year old. At what age did Ena's father get married?

Correct Answer: (c) 23 year
Solution:Present age of Ena = 13 year
Present age of her mother = (13 + 24) = 37 year
Age of Ena mother's when Ena born = 37 - 13 = 24 year
Age of Ena mother get married = 24 - 4 = 20 year
∴ Age of Ena father's = (20 + 3) = 23 year.

28. Mahesh is 60 year old. Ram is 5 year younger to Mahesh and 4 year elder to Raju. Babu is a younger brother of Raju and he is 6 year younger. What is the age difference between Mahesh and Babu?

Correct Answer: (b) 15 year
Solution:Here, age of Mahesh = 60 year
Ram is 5 yr younger to Mahesh.
∴ Age of Ram = 60 - 5 = 55 year
Ram is 4 year elder to Raju
∴ Raju's age = 55 - 4 = 51 year
Babu's is 6 yr younger to Raju
∴ Babu's age = 51 - 6 = 45
∴ Difference of age between Mahesh
and Babu = 60 - 45 = 15 year

29. The number of items in a booklet is N. In the first year there is an increase of x% in this number and in the subsequent year there is a decrease of x%. At the end of the two year, what will be the number of items in the booklet?

Correct Answer: (a) Less than N
Solution:


30. Solve the following equation

Correct Answer: (c)
Solution: