Please help me i’m being timed
1 answer:
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Answer:
Standard Deviation is 18.57 .
Step-by-step explanation:
We are given the frequency distribution for the speed of a sample of automobiles traveling on an interstate highway;
Speed (mph) Frequency (f) X X*f X -
50 - 54 4 52 208 52 - 65 = -13 169
55 - 59 3 57 171 57 - 65 = -8 64
60 - 64 2 62 124 62 - 65 = -3 9
65 - 69 5 67 335 67 - 65 = 2 4
70 - 74 2 72 144 72 - 65 = 7 49
75 - 79 <u> 5 </u> 77 <u> 385 </u> 77 - 65 = 12 144
<u> ∑f = 21 </u> ∑X*<u>f = 1367 </u>
Mean of the data, =
= = 65.09 ≈ 65 .
Now, Standard deviation, s =
s = =
= 18.57
Therefore, standard deviation is 18.57 .