Arithmetic (UPSC) Part- III

Total Questions: 50

31. The monthly incomes of X and Y are in the ratio of 4 : 3 and their monthly expenses are in the ratio of 3 : 2. However, each saves ₹ 6,000 per month. What is their total monthly income? [2017-II]

Correct Answer: (b) ₹ 42,000
Solution:Let the monthly incomes of x and y be 4x and 3x.
4x - 6000 = 3/2
So, 3x - 6000 = 3/2

⇒ 8x - 12000 = 9x - 18000
∴ x = ₹ 6,000
Total income of x and y = (3 + 4)x
= ₹ 6,000 × 7 = ₹ 42,000

32. Two walls and a ceiling of a room meet at right angles at a point P. A fly is in the air 1 m from one wall, 8 m from the other wall and 9 m from the point P. How many meters is the fly from the ceiling? [2017-II]

Correct Answer: (a) 4
Solution:9 = √(8)² + (1)² + (d)²

⇒ 81 = 64 + 1 + (d)² ⇒ (d)² = 16 ⇒ d = 4

33. A lift has the capacity of 18 adults or 30 children. How many children can board the lift with 12 adults? [2018-II]

Correct Answer: (b) 10
Solution:18 Adults = 30 children (given)

3 Adults = 5 children ∴ 1 adult = 5/3 children

12 Adults + x children = 18 Adults

12 × 5/3 children + x children = 18 × 5/3 children

x = 10 children

34. A person bought a refrigerator worth ₹ 22,800 with 12.5% interest compounded yearly. At the end of first year he paid ₹ 8,650 and at the end of second year ₹ 9,125. How much will he have to pay at the end of third year to clear the debt? [2018-II]

Correct Answer: (d) ₹ 11,250
Solution:Amount to be paid after 1 year
= 22800 + 22800 × 12.5/100 = 22800 + 2850 = 25650

He paid 8650 then amount left
= 25650 - 8650 = 17000
Amount to be paid after 2 years
= 17000 + 17000 × 12.5/100 = 17000 + 2125 = 19125

He paid 9125 at the end of 2nd year then remaining amount
= 19125 - 9125 = 10000
Amount to be paid at the end of 3rd year
= 10000 + 10000 × 12.5/100 = 11250

35. If x − y = 8, then which of the following must be true? [2018-II]

  1. Both x and y must be positive for any value of x and y.
  2. If x is positive, y must be negative for any value of x and y.
  3. If x is negative, y must be positive for any value of x and y.
    Select the correct answer using the code given below.
Correct Answer: (d) Neither 1 nor 2 nor 3
Solution:

Checking statement 1
x − y = 8
Both x and must be positive for any value of xx and.
It is not true because negative values of xx and yy or positive xx and negative is also possible.

Checking statement 2
If x is positive, y must be negative for any value of x and .
It is also not true because positive values of x and are also possible.

Checking statement 3
If is negative, y must be positive for any value of and .
Here if is negative then only negative value of is possible.
Hence, neither 1 nor 2 nor 3

36. A shopkeeper sells an article at ₹ 40 and gets X% profit. However, when he sells it at ₹ 20, he faces same percentage of loss. What is the original cost of the article? [2018-II]

Correct Answer: (c) ₹ 30
Solution:

37. There are 24 equally spaced points lying on the circumference of a circle. What is the maximum number of equilateral triangles that can be drawn by taking sets of three points as the vertices? [2018-II]

Correct Answer: (c) 8
Solution:

Each equilateral triangle is made by joining the three points as in the figure given below. Circle is divided into three sectors.

Hence, required number of triangles = 24 / 3 = 8

38. A number consists of three digits of which the middle one is zero and their sum is 4. If the number formed by interchanging the first number itself by 198, then the difference between the first and last digits is [2018-II]

Correct Answer: (b) 2
Solution:

39. A bookseller sold ‘a’ number of Geography textbooks at the rate of ₹ x per book, ‘a + 2’ number of History textbooks at the rate of ₹ (x + 2) per book and ‘a – 2’ number of mathematics textbooks at the rate of ₹ (x – 2) per book. What is his total sale in ₹? [2018-II]

Correct Answer: (b) 3ax
Solution:

40. A student has to get 40% marks to pass in an examination. Suppose he gets 30 marks and fails by 30 marks, then what are the maximum marks in the examination? [2018-II]

Correct Answer: (c) 150
Solution:Total passing marks = 30 + 30 = 60
Percentage of passing marks = 40%
Let total marks be x
According to the question
x × (40/100) = 60

∴ 60 × 100/40 = 150