Number System-Railway Maths Part IV

Total Questions: 50

41. The sum of the place values of 9 in 96961 is: [RRB NTPC 19/01/2021 (Morning)]

Correct Answer: (d) 90900
Solution:

There are two 9's in 96961 Their place values are = 90000 and 900
Sum = 90000 + 900 = 90900

42. Find the greatest number of five digits which is exactly divisible by 6, 8, 12, 15 and 20. [RRB NTPC 19/01/2021 (Morning)]

Correct Answer: (b) 99960
Solution:

LCM of 6,8, 12, 15 and 20 is = 120
The greatest number of 5 digit = 99999 When 99999/120 then the remainder is 39
If we subtract 39 from 99999, then number becomes divisible by 120 99999 - 39 = 99960 is exactly divisible by 120.

43. A terminating decimal is always: [RRB NTPC 19/01/2021 (Evening)]

Correct Answer: (c) a rational number
Solution:

A terminating decimal is always a rational number As it can be represented by p/q form.

44. The decimal expansion 31/2.5 of will terminate after: [RRB NTPC 19/01/2021 (Evening)]

Correct Answer: (b) one decimal place
Solution:

31/2.5= 12.4

45. The product of √4/6 and √3/24 is: [RRB NTPC 19/01/2021 (Evening)]

Correct Answer: (c) a rational number
Solution:

The product of 4√6 and 3√24 is 144 and it's a rational number.

46. (√2-√3)² is: [RRB NTPC 19/01/2021 (Evening)]

Correct Answer: (c) an irrational number
Solution:

On solving the term (√2 - √3)² = 2 + 3 - √6
is obtained and this irrational term.

47. The decimal expression of 3/8 comes to an end after how many digits after the decimal?? [RRB NTPC 20/01/2021 (Morning)]

Correct Answer: (a) 3
Solution:

3/8 = 0.375 i.e. the decimal expression of 3/8 comes to an end after 3 digits, after the decimal.

48. Find the number [RRB NTPC 20/01/2021 (Morning)]

Correct Answer: (c) a rational number
Solution:

49. Which of the following is a rational number between √5 and √7? [RRB NTPC 20/01/2021 (Morning)]

Correct Answer: (a)2⅖
Solution:

The rational number between
√5 ≅ 2.24 and √7 ≅ 2.65 = 2⅖ = 2.4

50. The 5th part of a number when divided by 3 yields three times half of tenth part of half of 80. What is the number? [RRB NTPC 20/01/2021 (Morning)]

Correct Answer: (c) 90
Solution:

Let the number is = N ;
According to the question,
⇒ N/(5 × 3) = 3 × 1/2 × 40/10 ⇒ N=90