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Question 146

A histogram of puzzle-completion times has the following frequency densities.

time t (s)0≤t<3030≤t<6060≤t<9090≤t<120120≤t<150frequency density11486\begin{array}{c|ccccc}\text{time }t\text{ (s)}&0\leq t<30&30\leq t<60&60\leq t<90&90\leq t<120&120\leq t<150\\\hline\text{frequency density}&1&1&4&8&6\end{array}time t (s)frequency density​0≤t<301​30≤t<601​60≤t<904​90≤t<1208​120≤t<1506​​

There are 120 people with completion time at least 150 seconds. Estimate the percentage who took less than 90 seconds.

[4]
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2 Statistics Questions

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