What percentage of the app's deliveries take…

What percentage of the app's deliveries take more than 46 minutes?

Question 51

EasyOriginal question

A food-delivery app's delivery times are normally distributed with mean 40 minutes and standard deviation 8 minutes. (Take $P(0 < Z < 0.5) = 0.1915$ , $P(0 < Z < 0.75) = 0.2734$ , $P(0 < Z < 1.645) = 0.45$ and $P(0 < Z < 2) = 0.4772$ .)

What percentage of the app's deliveries take more than 46 minutes?

21.66%Correct answerYour answer22.66%Correct answerYour answer27.34%Correct answerYour answer77.34%Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer B

Correct answer: B

$z = \frac{46 - 40}{8} = 0.75$ .
$0.5 - 0.2734 = 0.2266$ , so 22.66%.

Worth noting

27.34% is the share between 40 and 46 minutes.

Concept: An upper tail
Typical timeTypical: 90 s
Your timeYours: —

The rule this testsUsing the normal distribution

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Ten questions from Normal Distribution, at your own pace.

Practise this chapter →

Ten questions from Normal Distribution, at your own pace.

What percentage of the app's deliveries take more than 46 minutes?

Question 51

Explanation