The table shows the number of late arrivals recorded for each of 20 buses during one week. Number of

Question

The table shows the number of late arrivals recorded for each of 20 buses during one week. Number of late arrivals, $x$Frequency $0$$2$ $1$$5$ $2$$8$ $3$$4$ $4$$1$ Calculate the mean number of late arrivals.[2] Calculate the standard deviation of the number of late arrivals, correct to 3 significant figures.[2] A pupil enters each of the five values once into a calculator and obtains a mean of 2. Explain the mistake.[1]

Accepted Answer

(a) $1.85$ late arrivals (b) $1.01$ late arrivals (c) The frequencies were ignored.

Number of late arrivals, \(x\)	Frequency
\(0\)	\(2\)
\(1\)	\(5\)
\(2\)	\(8\)
\(3\)	\(4\)
\(4\)	\(1\)

Frequency-weighted spread

Frequency-weighted spread

Solution:

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