A company manufactures right-angled brackets for use in the construction industry. A sample of brackets are measured, and the number of degrees by which their angles deviate from a right angle are summarised in the following table.

a. Draw a cumulative frequency polygon to illustrate these deviations.

b. Estimate the median and the interquartile range of the bracket angles, giving both answers correct to 1 decimal place.

c. A bracket is considered unsuitable for use if its angle deviates from a right angle by more than 1.2°. Estimate what percentage of this sample is unsuitable for use, giving your answer correct to the nearest integer.

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Deviation from 90° (d) No, brackets (S) d<-1.5 -1.5