A teacher randomly selects 10 out of her 30 students and finds that the mean height of those 10 students is 5′2". Is this a sample mean or a population mean, and which symbol would be used to denote it?

Sample mean

Symbol:

Step-by-step explanation:

Given

Solving (a): Is it sample mean or population mean

From the question, we understand that 10 were selected from a total of 30.

And the mean of the selected 10 is 5'2"

The selected 10 is referred to as sample and the mean of the 10 is the sample mean

Solving (b): Symbol to use.

The symbol for sample mean is:

The answer is in the image 

The answer is in the image 

For every 8 cars there are 7 trucks

Therefore,

Cars:Truck=8:7

Answer is B)8:7

The solution is in the following image

y=2x+15

where y=Value of coin

x=Age in years

Value of coin after 19 years=2*19+15

=$53

Therefore, Value after 19 years=$53

The answer is in the image 

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.

30% of 420 are first year students

first year students = (30/100 )*420

=126 students

Student who are not in first year = 420-126

=294 students  

Area of rectangle= L*b

here,

L=12.4 cm

b= 8.8 cm

A= L*b

= 12.4 * 8.8 = 109.12 cm^2