Suppose the mean height in inches of all 9th grade students at one high school is estimated. The population standard deviation is inches. The heights of 10 randomly selected students are 75,62,69,65,66,64,67,70,74 and 63.

The population mean = sample mean = x`= 67.5

Population standard deviation = 13.369

Sample standard deviation= 4.225

Step-by-step explanation:

AS the population mean is not given we will calculate it from the sample.

The mean of the sampling distribution is equal to the population mean .

The sample mean is calculated by

x`= ∑x/n= 75,+ 62, +69,+65,+66,+64, +67,+70,+74 + 63/10

x`=675/10= 67.5

The standard deviation of the sample is equal to

u = σ/ √n   where σ is the population standard deviation and n is the number of observations.

Calculating the sample mean

s= √∑xi²/n- (∑x/n)²

s= √(45741/10)- (675/10)²

s= 4.2249

σ= u*√n= 4.229 *√10

σ=13.360

6 hours 48 min

step-by-step explanation:

68÷5=13.6

13.6×30=408min=6 hours 48 min.

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an = 22 + (n-1) *6

110 seats

step-by-step explanation:

an=a1+(n-1)(d)

a1 = 22   this is the first item in the sequence

d =6   this is how the sequence goes up

a)   an = 22 + (n-1) *6

b) a12 = 22 + (12-1) *6

    a12 = 22+11*6

  a12 = 22 +88

  a12 = 110