New Learning Composite Mathematics SK Gupta Anubhuti Gangal Class 8 Variation Self Practice 9A Solution
(1) Tell whether each relationship is a direct variation. Explain. If yes, state the constant of variation.
(a)
x | 1 | 2 | 3 | 4 |
y | 3 | 6 | 9 | 12 |
(b)
x | 10 | 5 | 3 |
y | 16 | 8 | 7 |
(c)
x | 4 | -1 | -5 |
y | -8 | 2 | 10 |
(2) Tell whether each relationship is a direct variation. Explain. If yes, state the constant of variation.
(a) y = -7x
(b) 4x – 3y = 11
(c) -8x + 5y = 0
(d) xy = 9
(3) The value of y varies directly with x, and y = 12 when x = 10, Find y when x = 25.
Solution:
(4) If p varies directly as q and if p = 21 when q = 7, then find q when p = 15.
(5) If the cost of petrol is Rs. 68.75 per litre, write a direct variation equation to describe the cost y of x litres of petrol.
(6) Tell whether each relationship is a direct variation. Explain your answer.
(a) The equation -18x + 7y = 0 relates the length of a videotape in centimeters x to its approximate playing time in seconds y.
(b) The equation y – 2.00x = 2.50 relates the cost y of a taxicab journey to distance x in km covered by the cab.
(7) Ragini bought an energy efficient washing machine. She will save about 15 litres of water per wash load.
(a) Write an equation of direct variation to describe how many litres of water y Ragini saves for x loads of laundry she washes.
(b) If Ragini does one load of laundry daily, how many litres of water will she save at the end of a year?
Solution:
(8) Think and answer. If you double an x-value in a direct variation, will the corresponding y-value double? Explain.
(9) The height of which a balloon and hydrogen gas rises in the air varies directly as time. Given below are some observations about the time and the corresponding height of the balloon (in metres). Find the missing terms in the table.
Time (in minutes) | 3 | 4 | _ | 25 | _ |
Height of the Balloon (in metres) | _ | 48 | 84 | _ | 1860 |
(10) If d varies directly as t, and if d = 4 when t = 9, find d when t = 21.
Solution:
(11) The mass of a uniform copper bar varies directly as its length. If a bar 40 cm long has a mass of approximately 420 g. Find the mass of a bar 136 cm long.
(12) A fish with a mass of 3 kg causes a fishing pole to bend 9 cm. If the amount of bending varies directly as the mass, how much will the pole bend for a 2 kg fish?
Solution:
(13) At a party, 8 bottles of soft dring are served for every batch of 5 children. How many bottles would be served if 40 children were present at the party?
(14) Harsh takes 150 steps in walking distance of 125 metres. What distance would he cover in 360 steps?
(15) The second class railway fare for 240 km of journey is Rs. 125. What would be the fare for a journey of 144 km? Assume that the fare varies directly as the length of the journey.
Solution:
Please write in food handwriting I am not able to understand and write line to line wise process please
Plzzz……write systematically I can’t understand what is written……..
as the book given in 2022-2023 session some questions are not matched ch number is different but this is not a big problem the main problem is this they haven’t written in a proper way.
Ok checking Priya