Two persons could fit new windows in house in 3 days.
(i) One of the persons fell ill before the work started. How long would the job take now?
(ii) How many persons would be needed to fit the windows in one day?
(i) One of the persons fell ill before the work started. How long would the job take now?
(ii) How many persons would be needed to fit the windows in one day?
Solution and Explanation
(i) Let the number of days required by 1 man to fit all the windows be x.
The following table is obtained.
| Number of persons | 2 | 1 |
|---|---|---|
| Number of days | 3 | x |
Lesser the number of persons, more will be the number of days required to fit all the windows.
Hence, this is a case of inverse proportion.
Therefore, \(2 × 3 = 1× x\)
\(x = 6 .\)
Hence, the number of days taken by 1 man to fit all the windows is 6.
(ii) Let the number of persons required to fit all the windows in one day be y. The following table is formed.
| Number of persons | 2 | y |
|---|---|---|
| Number of days | 3 | 1 |
Lesser the number of days, more will be the number of persons required to fit all the windows.
Hence, this is a case of inverse proportion.
Therefore, \(2 × 3 = y × 1\)
\(y = 6 \)
Hence, 6 persons are required to fit all the windows in one day.
Top Questions on Inverse Proportion
- If a box of sweets is divided among 24 children, they will get 5 sweets each. How many would each get, if the number of the children is reduced by 4?
- CBSE Class VIII
- Mathematics
- Inverse Proportion
- Rehman is making a wheel using spokes. He wants to fix equal spokes in such a way that the angles between any pair of consecutive spokes are equal. Help him by completing the following table.
Number of spokes 4 6 8 10 12 Angle between a pair of consecutive spokes 90° 60° … … …
(i) Are the number of spokes and the angles formed between the pairs of consecutive spokes in inverse proportion?
(ii) Calculate the angle between a pair of consecutive spokes on a wheel with 15 spokes.
(iii) How many spokes would be needed, if the angle between a pair of consecutive spokes is 40°?- CBSE Class VIII
- Mathematics
- Inverse Proportion
- A school has 8 periods a day each of 45 minutes duration. How long would each period be, if the school has 9 periods a day, assuming the number of school hours to be the same?
- CBSE Class VIII
- Mathematics
- Inverse Proportion
- A car takes 2 hours to reach a destination by travelling at the speed of 60 km/h. how long will it take when the car travels at the speed of 80 km/h?
- CBSE Class VIII
- Mathematics
- Inverse Proportion
- A factory required 42 machines to produce a given number of articles in 63 days. How many machines would be required to produce the same number of articles in 54 days?
- CBSE Class VIII
- Mathematics
- Inverse Proportion
Questions Asked in CBSE Class VIII exam
- In the tsunami 150,000 people died. How many animals died?
- CBSE Class VIII
- The Tsunami
- When he felt the earthquake, do you think Ignesious immediately worried about a tsunami? Give reasons for your answer. Which sentence in the text tells you that the Ignesious family did not have any time to discuss and plan their course of action after the tsunami struck?
- CBSE Class VIII
- The Tsunami
- Subtract 4p2q – 3pq + 5pq2 – 8p + 7q – 10 from 18 – 3p – 11q + 5pq – 2pq2 + 5p2q
- CBSE Class VIII
- Addition and Subtraction of Algebraic Expressions
Fill in the blanks using the correct form of the verbs in brackets.
My little sister is very naughty. When she ____ (come) back from school yesterday, she had _____(tear) her dress. We _____(ask) her how it had _____(happen). She ______(say) she _____ _____ (have, quarrel) with a boy. She _____ _____ (have, beat) him in a race and he _____ ____ (have, try) to push her. She _____ ____ (have, tell) the teacher and so he _____ _____ (have, chase) her, and she _____ _____ (have, fall) down and _____ _____ (have, tear) her dress.
- CBSE Class VIII
- The Best Christmas Present in the world
- Identify the part which vibrates to produce sound in the following instruments.
- Dholak
- Sitar
- Flute
- CBSE Class VIII
- Sound is Produced by a Vibrating Body