For the data set 7,5,10,11,12, the mean, x,is 9. what is the standard deviation

2.61

Step-by-step explanation:

Given data (x) :  7,5,10,11,12

Mean of the data :

Number of data values : n= 5

Now,

i.e.

Now, the standard deviation for this data is given by :-

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

answer: city needs 2.4 inches of rainfall more to match the record of 40 inches.

step-by-step explanation:

since we have given that

total annual rainfall a city record = 40 inches

this year, total rainfall recorded = 37.6 inches

number of inches of rainfall   is needed to match the record of 40 inches is given by

hence, city needs 2.4 inches of rainfall more to match the record of 40 inches.