Average
- In the afternoon, a student read 100 pages at the rate of 60 pages per hour. In the evening, when she was tired, she read 100 more pages at the rate of. 40 pages per hour. What was her average rate of reading, in pages per hour ?
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As per the given in question ,
Required average rate of reading = 100 + 100 100 + 100 60 40 Required average rate of reading = 200 5 + 5 3 2 Required average rate of reading = 200 10 + 15 6
Correct Option: C
As per the given in question ,
Required average rate of reading = 100 + 100 100 + 100 60 40 Required average rate of reading = 200 5 + 5 3 2 Required average rate of reading = 200 10 + 15 6 Required average rate of reading = 200 × 6 = 48 pages/hour 25
- 5 members of a team are weighed consecutively and their average weight calculated after each member is weighed. If the average weight increases by one kg each time, how much heavier is the last player than the first one ?
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Let Weight of first member = w kg
Weight of second member = (w + 2) kg
Weight of third member = (w + 4) kg
Weight of fourth member = (w + 6) kg
Weight of fifth member = (w + 8) kgCorrect Option: C
Let Weight of first member = w kg
Weight of second member = (w + 2) kg
Weight of third member = (w + 4) kg
Weight of fourth member = (w + 6) kg
Weight of fifth member = (w + 8) kg
∴ Difference = Weight of fifth member - Weight of first member
∴ Difference = w + 8 – w = 8 kg
- The average salary of all staff of a school is ₹10,000. The average salary of 20 teaching staff is ₹12,000 and that of non-teaching staff is ₹5000, the number of non-teaching staff will be
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The average salary of all staff of a school = ₹10,000
Let Number of non-teaching staff = n
∴ 20 × 12000 + n × 5000 = (n + 20) × 10000
⇒ 240000 + 5000n = (n + 20) × 10000
⇒ 240 + 5n = (n + 20) × 10
⇒ 10n – 5n = 240 – 200Correct Option: B
The average salary of all staff of a school = ₹10,000
Let Number of non-teaching staff = n
∴ 20 × 12000 + n × 5000 = (n + 20) × 10000
⇒ 240000 + 5000n = (n + 20) × 10000
⇒ 240 + 5n = (n + 20) × 10
⇒ 10n – 5n = 240 – 200
⇒ 5n = 40
⇒ n = 40 ÷ 5 = 8
- In a prep school, the average weight of 30 girls in a class among 50 students is 16 kg and that of the remaining students is 15.5 kg. What is the average weight of all the students in the class ?
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The average weight of 30 girls = 16 kg
Total weight of 30 girls = 16 × 30
The average weight of remaining 20 boys = 15.5 kg
Total weight of 20 boys = 15.5 × 20Required average weight = 30 × 16 + 20 × 15.5 50
Correct Option: B
The average weight of 30 girls = 16 kg
Total weight of 30 girls = 16 × 30
The average weight of remaining 20 boys = 15.5 kg
Total weight of 20 boys = 15.5 × 20Required average weight = 30 × 16 + 20 × 15.5 50 Required average weight = 480 + 310 = 790 = 15.8 kg 50 50
- 30 pens and 75 pencils altogether were purchased for ₹510. If the average price of a pencil was ₹2, what was the average price of a pen ?
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Let average cost of 1 pen = ₹y, then
From question ,
30y + 75 × 2 = 510
⇒ 30y = 510 – 150 = 360Correct Option: D
Let average cost of 1 pen = ₹y, then
From question ,
30y + 75 × 2 = 510
⇒ 30y = 510 – 150 = 360
⇒ y = 360 ÷ 30 = 12
