Answer: 18
Step-by-step explanation:
Answer:
Probability that the calculator works properly for 74 months or more is 0.04 or 4%.
Step-by-step explanation:
We are given that the life span of a calculator has a normal distribution with a mean of 60 months and a standard deviation of 8 months.
Firstly, Let X = life span of a calculator
The z score probability distribution for is given by;
Z =
~ N(0,1)
where,
= population mean = 60 months
= standard deviation = 8 months
Probability that the calculator works properly for 74 months or more is given by = P(X
74 months)
P(X
74) = P(
) = P(Z
1.75) = 1 - P(Z < 1.75)
= 1 - 0.95994 = 0.04
Therefore, probability that the calculator works properly for 74 months or more is 0.04 or 4%.
Answer:
(x + 7)^2 = 64
Step-by-step explanation:
x^2 + 23x – 19 = 9x - 4
x^2 + 23x - 9x = -4 + 19
x^2 + 14x = 15 = 0
Completing the square:
(x + 14/2)^2 - (14/2)^2 = 15
(x + 7)^2 - 49 = 15
(x + 7)^2 = 64