Answer:
number of hours Alexander family ‘s sprinkler work = 20
number of hours Morgan family ‘s sprinkler work = 30
Step-by-step explanation:
Given in the question,
water output rate for the Alexander family ‘s sprinkler = 40 L
water output rate for the Morgan family ‘s sprinkler = 20 L
Suppose, number of hours Alexander family ‘s sprinkler work = x
Suppose, number of hours Morgan family ‘s sprinkler work = y
Equation1
x + y = 50
Equation 2
40x + 20y = 1400
x = 50 - y
Put this value of x in equation 2
40(50-y) + 20y = 1400
2000 - 40y + 20y = 1400
-20y = 1400 - 2000
-20y = -600
y = 30
Put this value of y in equation 1 to get the value of x
x + 30 = 50
x = 50 - 30
x = 20
Answers my vary but what i got is 140 divided by 10 = 14
70 you solve by making a proportion 2.8/x =4/100
Answer:
0.6472 = 64.72% probability that a randomly selected page does not need to be retyped.
Step-by-step explanation:
In a Poisson distribution, the probability that X represents the number of successes of a random variable is given by the following formula:
In which
x is the number of sucesses
e = 2.71828 is the Euler number
is the mean in the given interval.
Poisson distribution with an average of three errors per page
This means that 
What is the probability that a randomly selected page does not need to be retyped?
Probability of at most 3 errors, so:

In which
Then

0.6472 = 64.72% probability that a randomly selected page does not need to be retyped.
Answer:
the first one
Step-by-step explanation: