B is false, since by the inclusion/exclusion principle,
By independence, we have 
, which is zero if either of 
or 
is 0, which isn't guaranteed.
Answer:
Mean age: 48
Standard deviation: 4
Step-by-step explanation:
a) Mean
The formula for Mean = Sum of terms/ Number of terms
Number of terms
= 42 + 54 + 50 + 54 + 50 + 42 + 46 + 46 + 48+ 48/ 10
= 480/10
= 48
The mean age is 48
b) Standard deviation
The formula for Standard deviation =
√(x - Mean)²/n
Where n = number of terms
Standard deviation =
√[(42 - 48)² + (54 - 48)² + (50 - 48)² +(54 - 48)² + (50 - 48)² +(42 - 48)² + (46 - 48)² + (46 - 48)² + (48 - 48)² + (48 - 48)² / 10]
= √-6² + 6² + 2² + 6² + 2² + -6² + -2² + -2² + 0² + 0²/10
=√36 + 36 + 4 + 36 + 4 + 36 + 4 + 4 + 0 + 0/ 10
=√160/10
= √16
= 4
The standard deviation of the ages is 4
Step 1: Convert 
, which is in radians into degrees. To convert it multiply by 
900/12
75
Step 2: 75 degrees isn't on the unit circle but 45 degrees and 30 degrees is. Since 45 + 30 = 75 you can use the cosine of 45 and 30 to find the exact value
cos45 = 
cos30 =
Step 3: Add the cos45 and cos30 to get cos5pi/12
Hope this helped!
Answer: 73
Step-by-step explanation:
Multiply using the FOIL method, then combine the real and imaginary parts of the expression.
73
Ah, the commutative property.
a + b = b + a
xy = yx
When using the commutative property - a good way to remember it is to think of a community, in which each community member helps one another to a mutual outcome.
Using the commutative property we can rearrange this equation into a more sensical format:
-8.9 + 6.7 - 1.1
6.7 - 1.1 - 8.9
6.7 - 1.1 = 5.6
5.6 - 8.9 = -3.3
