[填空题]
The cumulative frequency curve below shf yds*l v dta8ea6c e(;,/zc0(8q,huhj mt6lf own7l ;gin9d9uo1qc lf /dk bf58s the serving speed, in km/h, of a sample of 80 randomly chosen serves by Roger Federer, the famous Swiss p81cluig9dn/ 7b lf 9qn f;ko5drofessional tennis player.
Give your answers to the following correct to the nearest whole number, wherever applicable.
1. Estimate the minimum and maximum speeds of these serves. min = km/h max = km/h
2. Estimate the median speed of these serves. km/h
3. Estimate the lower and upper quatiles. $Q_1$ = km/h $ Q_2$ = km/h
4. Calculate the interquartile range.
5. Estimate the number of serves that had speed of more than 215 $\mathrm{~km} / \mathrm{h}$ .
The table below shows speeds of these serves.
6. Find the values of x and y . x = y =
7. Write down
(1) the modal class;
(2) the mid-interval value of the modal class.
8. Estimate the below using your Graphic Display Calculator.
(1) the mean speed of these serves; km/h
(2) the standard deviation. km/h
9. Estimate the percentage of the serves where the serving speed differs from the mean by no more than 20 $\mathrm{~km} / \mathrm{hr}$ . %
