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Nov 2016 p62 q4
3088
12% of people take more than t minutes to cook an egg.
A random sample of n people is taken. Find the smallest possible value of n if the probability that none of these people takes more than t minutes to cook an egg is less than 0.003.
Solution
The probability that a person takes more than t minutes is 0.12. Therefore, the probability that a person takes t minutes or less is 0.88.
The probability that none of the n people takes more than t minutes is given by:
\((0.88)^n < 0.003\)
Taking logarithms on both sides, we have:
\(n \log(0.88) < \log(0.003)\)
Solving for n gives:
\(n > \frac{\log(0.003)}{\log(0.88)}\)
Calculating the right-hand side:
\(n > 45.4\)
Since n must be an integer, the smallest possible value is: