[填空题]
The cumulative frequency curve below shows theyjk2e,igl26e s h). ws n*iem- serving speed, in kmrvf(hwr ,k(c fgb3 7v4/h, of a sample of 80 rkhf bvvc(7rr ,f4(3wgandomly chosen serves by Roger Federer, the famous Swiss professional 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 $\mathrm{~km} / \mathrm{hr}$ . %
