Answer:
I THINK IT IS B BECAUSE IT WOULD MAKE SENCE
Step-by-step explanation:
9.
Well the first has the angles being 3x+12,x,and 90 so they have to add up to 180 degrees because it is a triangle.
3x+12+x+90 = 4x+102 = 180 solve
4x+102=180
4x=78
x=19.5
Answer: 0.0688
Step-by-step explanation:
Given : Current research indicates that the distribution of the life expectancies of a certain protozoan is normal with a mean of 43 days and a standard deviation of 10.1 days.
i.e.
and 
Let x represents the life expectancies of a certain protozoan.
Sample size : n= 25
The probability that a simple random sample of 25 protozoa will have a mean life expectancy of 46 or more days. :-

[using z-value table]
Hence, the required probability = 0.0688
Answer:
P(H) = 13 ÷ 52
Step-by-step explanation:
The computation of the probability that the first card be the heart is given below:
We assume that each and every card in the deck would be likely to be the first card
Here we assume the Hi that represent the first card drawn be the heart
NOw
P(Hi) = 1 ÷ 52 for
1 < = i < =13.
The H event would be represent as the disjoint union
H = H1 U H2 U.....U H13
P(H) = 13 ÷ 52