Answer:
cos (
) = 
Decimal value: −0.9238795325...
Step-by-step explanation:
Write,
cos
= cos
= −cos 
Now using half angle formula, cos(x) = 2 cos²(
) − 1, we can write cos
= 2
cos²(
) − 1
This means
+ 1 = 2 cos²(
)
2 cos²(
) = 
cos²(
) = 
cos(
) = 
Simplify,
=
= 
Hence,
cos (
) = −cos (
) = 
Answer:
0.0023 = 0.23% probability that all 5 balls selected will be the same color
Step-by-step explanation:
A probability is the number of desired outcomes divided by the number of total outcomes.
The order in which the balls are selected is not important, which means that the combinations formula is used to solve this question.
Combinations formula:
is the number of different combinations of x objects from a set of n elements, given by the following formula.

Desired outcomes:
Either 5 amber from a set of 6, or 5 blue from a set of 5. So

Total outcomes:
5 balls selected from a set of 6 + 5 + 4 = 15. So

Probability:

0.0023 = 0.23% probability that all 5 balls selected will be the same color
Answer:
17 quarters, 37 nickels
Step-by-step explanation:
We just have to set up a system of equations
quarters are x
and nickels are y
x+y=54
0.25x+0.05y=6.10
now we can get ready to substitute
x=54-y
substitute it in
0.25(54-y)+0.05y=6.10
simplify/evaluate
13.5-0.25y+0.05y=6.10
-0.2y=-7.4
y=37
plug it back in
x+37=54
x=17
Answer:1.2
Step-by-step explanation: