Ratio And Proportion Questions For Railway Group-D PDF:
Download Ratio And Proportion Questions For Railway Group-D PDF with detailed solutions. Important Practice Ratio and Proportion questions based on previous year railway exam papers.
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Question 1: 35 is the average marks obtained by 120 students. The average marks of successful candidates was 39 and that of unsuccessful candidates was 15. What is the number of successful candidates in that examination ?
a) 100
b) 110
c) 120
d) 80
Question 2: A number of two digits is equal to ‘k’ times to the sum of these digits. If the places of the digits are mutually exchanged, the new formed number is equal to the sum of these digits multiplied by which one of the following options ?
a) 9 + k
b) 10 + k
c) 11 – k
d) k – 1
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Question 3: 45 is the average marks obtained by 30 students of a class. On checking, two errors were identified. On correction, one student obtained 45 more marks while other obtained 15 less marks. What is the average of corrected marks ?
a) 45
b) 44
c) 47
d) 46
Question 4: 5 years ago, average age of P and Q was 15 years. At present, average age of P, Q and R is 20 years. What will be the average age after 10 years ?
a) 35 years
b) 40 years
c) 30 years
d) 50 years
Question 5: The ratio of the present age of a man and his wife is 4:3 and 4 years hence the ratio of their ages will be 9:7 If the ratio of their ages at the time of their marriage was 13:9, how many years ago were they married ?
a) 4
b) 8
c) 6
d) 9
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Answers & Solutions:
1) Answer (A)
Let there be x successful candidates in the exam.
Unsuccessful candidates = 120 – x
Total score = 35 x 120
Total score is also equal to x * 39 + (120 – x) * 15
So, x = (35 * 120 – 120 * 15)/ 24 = 120 * 20 / 24 = 100
2) Answer (C)
Let the number be xy. So 10 x +y = k (x + y)
11 – k = 11- $ \frac{10x+y}{x+y}$ = $\frac{11x + 11y – 10x – y}{x+y}$
= $ \frac {10y + x}{x+y}$ which is inverse of the number divided by the sum of the digits.
Hence the required factor is 11 – k
3) Answer (D)
On correction, total increase in marks = 45 – 15 = 30 marks.
Number of students = 30
So, increase in the average = 30/30 = 1 mark.
4) Answer (C)
The average age increases with age. So, after 10 years, the average age is 20 + 10 = 30 years.
5) Answer (C)
Let the ages today be 4x and 3x. Ages four years from now are 4x + 4 and 3x + 4
But 4x+4:3x+4 = 9:7
So, x = 8
So, their current ages = 32 and 24
Let them be married for x years
Age at marriage = 32 – x and 24 – x
But 32 – x : 24 – x = 13: 9
So x = 6 years.
