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Last updated at Dec. 8, 2016 by Teachoo

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Example 5 The record of a weather station shows that out of the past 250 consecutive days, its weather forecasts were correct 175 times. (i) What is the probability that on a given day it was correct? The total number of days for which the record is available = 250 Number of days when forecast was correct = 175 P(the forecast was correct on a given day) = (๐๐ข๐๐๐๐ ๐๐ ๐๐๐ฆ๐ ๐๐๐ ๐คโ๐๐ ๐๐๐๐๐๐๐ ๐ก ๐ค๐๐ ๐๐๐๐๐๐๐ก)/(๐๐๐ก๐๐ ๐๐ข๐๐๐๐ ๐๐ ๐๐๐ฆ๐ ๐๐๐ ๐คโ๐๐โ ๐กโ๐ ๐๐๐๐๐๐ ๐๐ ๐๐ฃ๐๐๐๐๐๐๐) = 175/250 = 0.7 Example 5 (Method 1) The record of a weather station shows that out of the past 250 consecutive days, its weather forecasts were correct 175 times. (ii) What is the probability that it was not correct on a given day? The total number of days for which the record is available = 250 The number of days when the forecast was not correct = 250 โ 175 = 75 P(the forecast was not correct on a given day) = (๐๐ข๐๐๐๐ ๐๐ ๐๐๐ฆ๐ ๐๐๐ ๐คโ๐๐ ๐๐๐๐๐๐๐ ๐ก ๐ค๐๐ ๐๐๐ก ๐๐๐๐๐๐๐ก)/(๐๐๐ก๐๐ ๐๐ข๐๐๐๐ ๐๐ ๐๐๐ฆ๐ ๐๐๐ ๐คโ๐๐โ ๐กโ๐ ๐๐๐๐๐๐ ๐๐ ๐๐ฃ๐๐๐๐๐๐๐) = 75/250 = 0.3 Example 5 (Method 2) The record of a weather station shows that out of the past 250 consecutive days, its weather forecasts were correct 175 times. (ii) What is the probability that it was not correct on a given day? P(the forecast was not correct on a given day) = 1 โ P(forecast was correct on a given day) = 1 โ 0.7 = 0.3

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.