Answer:

Step-by-step explanation:
-For a known standard deviation, the sample size for a desired margin of error is calculated using the formula:

Where:
is the standard deviation
is the desired margin of error.
We substitute our given values to calculate the sample size:

Hence, the smallest desired sample size is 23
Answer:
7 cm²
Step-by-step explanation:
Area of a triangle = (Base * hight) / 2
A = (2* 7) /2 = 14/ 2 = 7 cm²
Answer:
-2.25
Step-by-step explanation:
9(1-x) = 27Y
9-9x =27y
-9x -27y = -9 multiply all terms by -1
9x +27y =9 equation (1)
x-y= -11/2 equation (2)
by solving 2 equations
x= -3.875
y= 1.625
∴ x+ y = 1.625 +(-3.875) = -2.25
Answer:


Step-by-step explanation:
Given the matrices


Calculating AB:

Multiply the rows of the first matrix by the columns of the second matrix


Hence,

Therefore,


Answer:
13.2
Step-by-step explanation: