Answer:
See explanation below.
Step-by-step explanation:
Assuming the distribution on the figure attached. We have a distribution skewed to the right.
We can calculate the deviation with the following table:
Class frequency(f) (Xm) Midpoint f*Xm fXm^2
50-90 28 70 1960 137200
90-130 32 110 3520 387200
130-170 18 150 2700 405000
170-210 8 190 1520 288800
210-250 8 230 1840 423200
290-330 2 310 620 192200
410-450 2 430 860 369800
Total 98 13020 2203400
We are assuming the frequencies that;s important to mention.
We can calculate the sample variance with the following formula:
[tex] s^2 = \frac{\sum f X_m^2 -[\frac{(\sum f Xm)^2}{n}]}{n-1}[/tex]
And if we replace we got:
[tex] s^2 = \frac{2203400 -\frac{(13020)^2}{98}}{97}= 4882.474[/tex]
And then the standard deviation is given bY:
[tex] s = \sqrt{4882.474}=69.87[/tex]
So then the best answer would be : 70
