3 years ago

15 less than 3 times a number is 5 more than half of the number.

Mathematics

1 answer:

ohaa [14]3 years ago

7 0

Answer:

Mystery Number is 8

Step-by-step explanation:

3x - 15 = 5 + 1/2x

3x - 1/2x = 15 + 5

5/2x = 20

x = 20 / 5/2

x = 20 * 2/5

x = 40 / 5

x = 8

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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

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