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標題:
maths sequence <<<<>>>>>
發問:
An earthworm starts moving towards a point 1.8cm away at a pace of 1cm per minute. As it gets tired, it covers only half the distance compared to previous minute in each succeeding minute. How long will it take to reach its target? thanks
最佳解答:
1.8cm = 1cm + 0.5cm +0.25cm + 0.125cm + ... + (0.5 ^ n) = {1 - [0.5 ^ (n + 1)]} / (1 - 0.5) = {1 - [0.5 ^ (n + 1)]} / 0.5 so, 0.1 = [0.5 ^ (n + 1)] ln (0.1) = ln [0.5 ^ (n + 1)] n = ln (0.1) / ln (0.5) - 1 = 2.322
其他解答:
maths sequence <<<<>>>>>
發問:
An earthworm starts moving towards a point 1.8cm away at a pace of 1cm per minute. As it gets tired, it covers only half the distance compared to previous minute in each succeeding minute. How long will it take to reach its target? thanks
最佳解答:
1.8cm = 1cm + 0.5cm +0.25cm + 0.125cm + ... + (0.5 ^ n) = {1 - [0.5 ^ (n + 1)]} / (1 - 0.5) = {1 - [0.5 ^ (n + 1)]} / 0.5 so, 0.1 = [0.5 ^ (n + 1)] ln (0.1) = ln [0.5 ^ (n + 1)] n = ln (0.1) / ln (0.5) - 1 = 2.322
其他解答:
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