πRemember the Important Formula's for solving CSAT Questions from this Topic.
Topic: 20 β Clock
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Topic: 20 β Clock
Join: @CSAT_2023
β€5
The average marks of a group of 20 students on a test is reduced by 4 when the topper who scored 90 marks is replaced by a new student. How many marks did the new student have?
Anonymous Quiz
9%
(a) 30
50%
(b) 10
25%
(c) 20
16%
(d) 40
π8
A street vendor has enough money to buy 20 pairs of shoes. If he gets discount of Rs. 25 on each pair of shoe, then he can buy two more pairs of shoes, and still have Rs. 70 left with him. How much money did he have originally?
Anonymous Quiz
5%
(a) Rs. 4500
71%
(b) Rs. 4800
18%
(c) Rs. 5000
5%
(d) Rs. 5200
π7π₯1
πAns. B | Explanation:
Let the original price of each pair of shoe be Rs. x.
According to the question,
20x = 22(x β 25) + 70
or, 20x = 22x β 550 + 70
or, 22x β 20x = 480
or, 2x = 480
or, x = Rs. 240
So, the amount of money that street vendor originally had = 20x = 20 Γ 240 = Rs. 4800
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Let the original price of each pair of shoe be Rs. x.
According to the question,
20x = 22(x β 25) + 70
or, 20x = 22x β 550 + 70
or, 22x β 20x = 480
or, 2x = 480
or, x = Rs. 240
So, the amount of money that street vendor originally had = 20x = 20 Γ 240 = Rs. 4800
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π10β€1
A man in his boat can cover 60 km length of a river and come back to his initial point in 4 hrs. If speed of boat is twice that of stream, then what must be the speed of stream?
Anonymous Quiz
19%
a) 15 km/hr
19%
(b) 16 km/hr
54%
(c) 20 km/hr
9%
(d) 10 km/hr
π3β€1
πAns. C | Explanation:
Let, speed of stream = x km/hr.
So, speed of boat = 2x km/hr.
According to the question,
[60/(2x + x)] + [60/(2x - x)] = 4
Or (60/3x) + (60/x) = 4
Or (20/x) + (60/x) = 4
Or 80/x = 4
Or x = 20 km/hr
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Let, speed of stream = x km/hr.
So, speed of boat = 2x km/hr.
According to the question,
[60/(2x + x)] + [60/(2x - x)] = 4
Or (60/3x) + (60/x) = 4
Or (20/x) + (60/x) = 4
Or 80/x = 4
Or x = 20 km/hr
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π5
A scored 60 more marks than B in an examination. If B scored 10% less marks than A, then how much did B score?
Anonymous Quiz
9%
(a) 360
14%
(b) 480
72%
(c) 540
5%
(d) 420
π5
πAns. C | Explanation:
A scored 60 more marks than B. So, if marks of B are b, then marks of A will be b + 60.
Now, B scored 10% less marks than A. That is, marks of B are 90% of the marks of A.
So, b = 90% of (b + 60)
Or 10b = 9b + 540
Or b = 540
So, B scored 540 marks.
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A scored 60 more marks than B. So, if marks of B are b, then marks of A will be b + 60.
Now, B scored 10% less marks than A. That is, marks of B are 90% of the marks of A.
So, b = 90% of (b + 60)
Or 10b = 9b + 540
Or b = 540
So, B scored 540 marks.
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π2
If the fifth day of a month is Monday, then which one of the following will be the third day from 18th of that month?
Anonymous Quiz
55%
(a) Wednesday
18%
(b) Thursday
17%
(c) Monday
10%
(d) Sunday
π5
πAns. A | Explanation:
Third day from 18th will be 21st.
Mondays of the month will be: 5 12 19 26
Hence, 21st of the month will be a Wednesday.
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Third day from 18th will be 21st.
Mondays of the month will be: 5 12 19 26
Hence, 21st of the month will be a Wednesday.
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π6
A man completes 5/8th of a job in 25 days. How many more days will it take him to finish the job if quantum of work is further increased by 50%?
Anonymous Quiz
10%
(a) 44 days
18%
(b) 31 days
14%
(c) 28 days
57%
(d) 35 days
π3
πAns. D | Explanation:
Let initial units of work = 8 units
Out of which, 5 units are completed in 25 days.
So, the number of days that the man takes in completing one unit of work = 25/5 = 5 days
Now, amount of new work = 8 + 50% of 8 = 8 + 4 = 12 units
Work remaining = 12 β 5 = 7 units
So, the time taken by the man to complete the rest of the work = 7 Γ 5 = 35 days
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Let initial units of work = 8 units
Out of which, 5 units are completed in 25 days.
So, the number of days that the man takes in completing one unit of work = 25/5 = 5 days
Now, amount of new work = 8 + 50% of 8 = 8 + 4 = 12 units
Work remaining = 12 β 5 = 7 units
So, the time taken by the man to complete the rest of the work = 7 Γ 5 = 35 days
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π9π₯1
What are the total number of five-digit numbers divisible by 5, that can be formed by using digits 1, 2, 3, 4, and 5, such that no digit is repeated?
Anonymous Quiz
21%
(a) 120
10%
(b) 8
63%
(c) 24
6%
(d) 36
π6
πAns. C | Explanation:
As the number is divisible by 5, so the unit place will always be 5.
The rest of the four positions may be filled by the remaining 4 digits as follows:
* Tens place in 4 ways
* Hundreds place in 3 ways
* Thousands place in 2 ways
* Ten Thousands place in 1 way
Hence, total number of required numbers = 4 Γ 3 Γ 2 Γ 1 = 24
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As the number is divisible by 5, so the unit place will always be 5.
The rest of the four positions may be filled by the remaining 4 digits as follows:
* Tens place in 4 ways
* Hundreds place in 3 ways
* Thousands place in 2 ways
* Ten Thousands place in 1 way
Hence, total number of required numbers = 4 Γ 3 Γ 2 Γ 1 = 24
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π7
In a city, 20% families read only two newspapers, 40% of the remaining read three newspapers and the remaining families read only one newspaper. Which of the following statements must definitely be true?
Anonymous Quiz
6%
(a) Only 20% of the total families read three newspapers.
53%
(b) 48% of the total families read only one newspaper.
35%
(c) 60% of the total families read at least two newspapers.
6%
(d) 88% of the total families read at least one newspaper.
π5
πAns. B | Explanation:
Let total number of families be 100.
Then, number of families reading only 2 newspapers = 20
Number of families reading 3 newspapers = 40% of (100 β 20) = 40% of 80 = 32
Number of families reading only 1 newspaper = 100 β (20 + 32) = 100 β 52 = 48
Thus, 48% of the total families read only one newspaper.
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Let total number of families be 100.
Then, number of families reading only 2 newspapers = 20
Number of families reading 3 newspapers = 40% of (100 β 20) = 40% of 80 = 32
Number of families reading only 1 newspaper = 100 β (20 + 32) = 100 β 52 = 48
Thus, 48% of the total families read only one newspaper.
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π6
A street vendor has enough money to buy 20 pairs of shoes. If he gets discount of Rs. 25 on each pair of shoe, then he can buy two more pairs of shoes, and still have Rs. 70 left with him. How much money did he have originally?
Anonymous Quiz
11%
(a) Rs. 4500
73%
(b) Rs. 4800
13%
(c) Rs. 5000
2%
(d) Rs. 5200
π5
πAns. B | Explanation:
Let the original price of each pair of shoe be Rs. x.
According to the question,
20x = 22(x β 25) + 70
or, 20x = 22x β 550 + 70
or, 22x β 20x = 480
or, 2x = 480
or, x = Rs. 240
So, the amount of money that street vendor originally had = 20x = 20 Γ 240 = Rs. 4800
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Let the original price of each pair of shoe be Rs. x.
According to the question,
20x = 22(x β 25) + 70
or, 20x = 22x β 550 + 70
or, 22x β 20x = 480
or, 2x = 480
or, x = Rs. 240
So, the amount of money that street vendor originally had = 20x = 20 Γ 240 = Rs. 4800
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π7
In a certain code language, βNOTEβ is coded as βMONPSUDFβ. How will βROADβ be coded as in that language?
Anonymous Quiz
66%
(a) QSNPZBCE
15%
(b) QSMPZBCE
11%
(c) QSNQZBCE
7%
(d) QSNPYBCE
π6
How many pairs of digits in the number 543968 have as many numbers between them as in the series of natural numbers (consider both backward and forward directions)?
Anonymous Quiz
12%
(a) Only one
42%
(b) More than one but less than three
38%
(c) More than three
9%
(d) Only three
π1