Answer:
The proportion is 2/7 = 12/42
x = 12
The answer is 12
-4m-8=-8-4m
+4 +4
__________
-8=-8
or
1=1
Answer:
a. P(x>20)=0.19
b. P(x≥6)=0.72
c. P(x≤20)=0.81
d. A and C
Step-by-step explanation:
We know that:
1) the probability that a student makes fewer than 6 mistakes is 0.28
![P(x](https://tex.z-dn.net/?f=P%28x%3C6%29%3D0.28)
2) The probaiblity that a student makes between 6 to 20 mistakes is 0.53.
![P(6\leq x\leq20)=0.53](https://tex.z-dn.net/?f=P%286%5Cleq%20x%5Cleq20%29%3D0.53)
We will express the proabilibities in function of the information we have.
a. Probability that a student makes more than 20 mistakes.
![P(x>20)=1-P(x\leq20)=1-(P(x20)=1-(0.28+0.53)=1-0.81=0.19](https://tex.z-dn.net/?f=P%28x%3E20%29%3D1-P%28x%5Cleq20%29%3D1-%28P%28x%3C6%29%2BP%286%5Cleq%20x%20%5Cleq20%29%29%5C%5C%5C%5CP%28x%3E20%29%3D1-%280.28%2B0.53%29%3D1-0.81%3D0.19)
b. Probability that the student make 6 or more mistakes
![P(x\geq6)=1-P(Px](https://tex.z-dn.net/?f=P%28x%5Cgeq6%29%3D1-P%28Px%3C6%29%3D1-0.28%3D0.72)
c. Probability that a student makes 20 mistakes at most
![P(x\leq20)=P(x](https://tex.z-dn.net/?f=P%28x%5Cleq20%29%3DP%28x%3C6%29%2BP%28x%5Cleq%20x%5Cleq20%29%3D0.28%2B0.53%3D0.81)
d. A and C, because A takes a event of more than 20 mistakes and C takes the event of 20 or less mistakes. Both events cover a probability of 1.
7cos(x) + 1 = 6sec(x)
7cos(x) + 1 = 6/cos(x)
7cos^(x) + cos(x) = 6
7cos^(x) + cos(x) - 6 = 0
[7cos(x) - 6][cos(x) + 1] = 0
cos(x) = 6/7 , x = arccos(6/7) and
cos(x) = -1, x = 180