Three missiles are fired at an enemy arsenal. the probabilities the individual missile will hit the arsenal are 0.75, 0.85, and 0.9. find the probability that at least two of the missiles hit the arsenal..

The probability that at least two of the missiles hit the arsenal:
P ( x ≥ 2 ) = P ( x = 2 ) + P ( x = 3 )
P ( x = 2 ) = 0.75 · 0.85 · 0.1 + 0.85 · 0.9 · 0.25 + 0.75 · 0.9 · 0.15 =
= 0.06375 + 0.10125 + 0.19125 = 0.35625
P ( x = 3 ) = 0.75 · 0.85 · 0.9 = 0.57375
P ( x ≥ 2 ) = 0.35625 + 0.57375 = 0.93

The probability is 0.93 or 93%. 

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post

Period is the time it takes for one “cycle” to complete. in the parent sine function, period is 2*pi since sin(0) = 0, sin(pi/2) = 1, sin(pi) = 0, sin(3pi/2) = -1, and sin(2pi) = 0. at that point, the sequence repeats itself. i’m not sure if your graph is similar to the sine function since you didn’t provide a picture, but you can find the period by looking at a graph.