Let X be the number of lightning strikes in a year at the top of particular mountain.
X follows Poisson distribution with mean μ = 3.8
We have to find here the probability that in randomly selected year the number of lightning strikes is 0
The Poisson probability is given by,
P(X=k) = 
Here we have X=0, mean =3.8
Hence probability that X=0 is given by
P(X=0) = 
P(X=0) = 
P(X=0) = 0.0224
The probability that in a randomly selected year, the number of lightning strikes is 0 is 0.0224
Answer:
The probability is 0.9909.
Step-by-step explanation:
Test statistic (z) = (sample mean - population mean) ÷ (sd/√n)
sample mean = 290 days
population mean = 298 days
sd = 22 days
n = 42
z = (290 - 298) ÷ (22/√42) = -8 ÷ 3.395 = -2.36
The cumulative area of the test statistic is the probability that the mean gestation period is less than 290 days. The cumulative area is 0.9909. Therefore the probability is 0.9909.
He had saved 320 initially
Step-by-step explanation:
Let the amount he saved be 'a'
Amount spent = 20 + 40 + 30
= 90
His grand father gave 50
At the end he has 280
280 = a - 90 +50
a = 280 -50 +90
= 320
He had saved 320 initially
