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

Total Questions: 100

31. Students of a class are made to sit in rows of equal number of chairs. If number of students is increased by 2 in each row, then the number of rows decreases by 3. If number of students is increased by 4 in each row, then the number of rows decreases by 5. What is the number of students in the class ?

Correct Answer: (d) 120
Solution:Let the numbers of row = x

32. A sum was put at simple interest at certain rate for 2 year. Had it been put at 1% higher rate of interest, it would have fetched ₹ 24 more. What is the sum?

Correct Answer: (a) ₹ 500
Solution:Let ₹ x was put at simple interest at rate of r% per annum for 2 year.

33. The population of two villages is 1525 and 2600 respectively. If the ratio of male to female population in the first village is 27 : 34 and the ratio of male to female population in the second village is 6 : 7, then what is the ratio of male to female population of these two villages taken together ?

Correct Answer: (d) 5 : 6
Solution:Given population of first village = 1525



34. In a class room the ratio of number of girls to that of boys is 3 : 4. The average height of students in the class is 4.6 feet. If the average height of the boys in the class is 4.8 feet, then what is the average height of the girls in the class ?

Correct Answer: (c) More than 4.3 feet but less than 4.4 feet
Solution:Let Number of girls = 3x and number of boys = 4x

35. What is the median of the data 3, 5, 9, 4, 6, 11, 18 ?

Correct Answer: (a) 6
Solution:Given data 3, 5, 9, 4, 6, 11, 18.
Now, arranging in ascending order 3, 4, 5, 6, 9, 11, 18
∴ Median = 6

36. In a pie-diagram there are three sectors. If the ratio of the angles of the sectors is 1 : 2 : 3, then what is the angle of the largest sector?

Correct Answer: (b) 180°
Solution:Let angles of three sectors are x, 2x and 3x.

37. The maximum marks in a test are converted from 250 to 50 for the purpose of an Internal Assessment. The highest marks scored were 170 and lowest marks were 70. What is the difference between the maximum and minimum marks scored in the Internal Assessment ?

Correct Answer: (c) 20
Solution:Since maximum marks in a test are converted from 250 to 50 for the Internal Assessment.

38. (Questions 38-40) Read the following information and answer the given questions follow.

The following data presents count of released convicts who have served prison terms (X), those who have received some educational or technical training during their term (Y) and those who were offered Company placement (Z) respectively, from six different jails A, B, C, D, E and F, in the year 2010.

XYZ
A864525
B1305903461
C2019940474
D1166869416
E954544254
F1198464174

Jails with highest and smallest percentage of trained convicts are respectively

Correct Answer: (b) D and F
Solution:Total released convicts from point A = 86 + 45 + 25 = 156



39. Jail with highest placement rate of trained convicts is

Correct Answer: (d) A
Solution:

40. Jails from which more than half of the trained convicts are offered jobs, are

Correct Answer: (a) A, B and C
Solution: