If sin Ф=1/3>0 and tan Ф<0; then Ф belongs to the second quadrant and cos Ф will be negative (cos Ф<0).
sin²Ф+cos²Ф=1
(1/3)²+cos²Ф=1
1/9+cos²Ф=1
cos²Ф=1-1/9
cos²Ф=8/9
cos Ф=⁺₋√(8/9)=⁺₋2√2 / 3
We have two possible solutions.
cos Ф=2√2 / 3 This solutions is not possible, because in this case cos Ф has to be negative (cos Ф<0)
cos Ф=(-2√2) / 3 this solutions is right.
answer:B. -2 square root 2 /3 (or (-2√2) /3 )
2.75 as a mixed number would be:
Answer:
Step-by-step explanation:
Given that the height in inches, of a randomly chosen American woman is a normal random variable with mean μ = 64 and variance 2 = 7.84.
X is N(64, 2.8)
Or Z = 
a) the probability that the height of a randomly chosen woman is between 59.8 and 68.2 inches.

b) 
c) For 4 women to be height 260 inches is equivalent to
4x will be normal with mean (64*4) and std dev (2.8*4)
4x is N(266, 11.2)

d) Z is N(0,1)
E(Z19) = 
since normal distribution is maximum only between 3 std deviations form the mean on either side.
Step 1- Multiply both sides by 8.
Step 2- Simplify 3 x 8 to 24.
Answer = x > 24