Your Progress - Chapter 110% complete
1Exercises6 questions
Q.1If the cost of 5 pens is Rs 60, find the cost of 8 pens.v
Solution
Cost is directly proportional to number of pens. Cost of 1 pen = Rs 12, so 8 pens cost Rs 96.
Answer:
Rs 96.
Q.2A car travels 240 km in 4 hours at a constant speed. How far will it travel in 7 hours?v
Solution
Speed $=240/4=60$ km/h. Distance in 7 hours $=60\times7=420$ km.
Answer:
$420$ km.
Q.3If 6 workers complete a job in 10 days, how many days will 15 workers take?v
Solution
Workers and time are inversely proportional. $6\times10=15\times d$, so $d=4$.
Answer:
4 days.
Q.4If 12 taps fill a tank in 20 minutes, how long will 8 taps take?v
Solution
Number of taps and time are inversely proportional. $12\times20=8\times t$, so $t=30$.
Answer:
30 minutes.
Q.5How do you recognise direct proportion?v
Answer:
Two quantities are in direct proportion if one increases or decreases in the same ratio as the other and the ratio of the two remains constant.
Q.6How do you recognise inverse proportion?v
Answer:
Two quantities are in inverse proportion if an increase in one causes a proportional decrease in the other and their product remains constant.