Answer:
Donuts cost $2.00 and Cookies cost $1.50
Step-by-step explanation:
D = cost of a donut
C = cost of a cookie
4D + 10C = $23.00
8D + 6C = $25.00
Eliminate a variable when subtracting the two equations. Change both values with C to 60 in order to eliminate the C variable and solve for D.
80D + 60C = $250.00 subtracted from 24D + 60C = $138
56D = $112.00 (Divide by 56 to single out the variable)
56D/56 = $112.00/56
D = $2.00
Use the D value to solve for C.
4(2) + 10C = $23.00
8 + 10C = $23.00
8 - 8 + 10C = $23.00 - 8
10C = $15.00
10C/10 = $15/10
C = $1.50
Check:
Bentley:
4D + 10C = $23
4(2) + 10(1.50) = $23
8 + 15 = $23
23 = 23
Skylar:
8D + 6C = $25
8(2) + 6(1.50) = $25
16 + 9 = $25
25 = 25
Answer:

And we can calculate the mean with the following formula:

We can calculate the sample variance with this formula:

And the sample deviation would be given by:

Step-by-step explanation:
For this case we have the following data given:
7.9 9.7 9.7 8.7 7.0 7.2 11.3 11.8 7.3 8.1 8.0 11.6 6.8 9.0 6.3 7.0 7.4 8.7 6.8 5.8 7.8 7.7 6.3 7.0 7.7 6.5 10.7
Our variable of interest is given by X="flexural strength (MPa) for concrete beams of a certain type"
And for this case we know that 
And we can calculate the mean with the following formula:

We can calculate the sample variance with this formula:

And the sample deviation would be given by:

Everything outside the parabola. Point E and point A.
Answer:
Step-by-step explanation: