Paper 1 · Mathematical Reasoning and Aptitude
UGC NET December 2023 Re-Exam (14.12.2023) Shift-I
A car starts running with an initial speed of 50 km/hour, with its speed increasing every hour by 5 km/hour. How many hours will it take to cover a distance of 630 km?
A7 hours
B9 hours ✓ Correct
C6 hours
D8 hours
Correct answer: (B) 9 hours — The car takes 9 hours to cover 630 km, so the answer is 9 hours.
Explanation
★The car takes 9 hours to cover 630 km, so the answer is 9 hours.
★The distance in each successive hour increases by 5 km, forming an arithmetic progression.
★The hourly distances are 50, 55, 60, 65, 70, 75, 80, 85 and 90 km.
★This is an arithmetic series with first term 50 and common difference 5.
★The sum of these nine terms is 630 km.
★Since the ninth term completes 630 km, the total time is 9 hours.
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