Practice

Practise until it sticks

Choose a topic, a skill or a difficulty. Calculation exercises have new versions with fresh numbers once you have solved them, so you can practise the method rather than memorise an answer.

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Practice, difficulty 2 of 3

The 90th percentile

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A help desk measured the resolution time (minutes) of 15 tickets:

395, 137, 173, 409, 121, 145, 376, 436, 205, 258, 420, 303, 371, 457, 282

The service target is set at the 90th percentile. Find it with the type 7 method, to 1 decimal place.