3 years ago

Deena drove 585 miles in 9 hours. Kristen drove 605 miles in 11 hours. Who drove at a faster rate? How do you know?

Mathematics

1 answer:

Rashid [163]3 years ago

7 0

Divide miles driven by time and compare them.

Deena: 585 /9 = 65 miles per hour

Kristen: 605 /11 = 55 miles per hour

Deena drove at a faster rate because 65 is greater than 55.

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Help me find Sample variance and standard deviation

AnnZ [28]

First, find the mean. You'll need it to compute the variance.

$\bar x=\displaystyle\frac15\sum_{i=1}^5x_i=\dfrac{21+10+6+7+11}5=11$

The variance of the sample is then computed with the formula

$s^2=\displaystyle\dfrac1{5-1}\sum_{i=1}^5(\bar x-x_i)^2=\dfrac{(21-11)^2+\cdots+(11-11)^2}4=\dfrac{71}2=35.5$

The standard deviation is the square root of the variance, so

$s=\sqrt{35.5}\approx5.958$