Question 20: How many 3-digit numbers can be formed from the digits 0, 3, 4, 5, 7, 8 and 9,...
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How many 3-digit numbers can be formed from the digits 0, 3, 4, 5, 7, 8 and 9, which are divisible by 4 and none of the digits have been repeated?
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Answer: D. D) 30
X runs at 9.6 km/h = 8/3 m/s, taking 240 / (8/3) = 90 s. Y takes 90 + 6 = 96 s to finish 240 m. Y's speed = 240 / 96 = 2.5 m/s = 2.5 * 18/5 = 9 km/hr.
Step-by-step Derivation:
Step 1: Speed of X = 9.6 * (5/18) = 8/3 m/s.
Step 2: Time for X to complete 240m = 240 / (8/3) = 90 seconds.
Step 3: Time taken by Y = 90 + 6 = 96 seconds.
Step 4: Speed of Y = 240 / 96 = 2.5 m/s.
Step 5: Convert to km/h: 2.5 * (18/5) = 9 km/hr.