Question 4 - Figure it out - Page 84, 85 - Chapter 4 Class 7 - Expressions using Letter-Numbers (Ganita Prakash)

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Question 4 Venkatalakshmi owns a flour mill. It takes 10 seconds for the roller mill to start running. Once it is running, each kg of grain takes 8 seconds to grind into powder. Which of the expressions below describes the time taken to complete grind ‘y’ kg of grain, assuming the machine is off initially? (a) 10 + 8 + y (b) (10 + 8) × y (c) 10 × 8 × y (d) 10 + 8 × y (e) 10 × y + 8Given that Time taken to start running = 10 seconds Time taken to grind 1 kg of grain = 8 seconds We have to find time taken to grind ‘y’ kg of grain Now, Time taken to grind ‘y’ kg of grain = Time taken to start running + y × Time taken to grind 1 kg grain = 10 + y × 8 = 10 + 8y This matches with option (d)