According to the college board, sat critical reading scores from the 2014 school year for high school students in the united states were normally distributed with a mean of 497 and a standard deviation of 115. use a standard normal table such as this one to determine the probability that a randomly chosen high school student who took the sat in 2014 will have a critical reading sat score between 450 and 750 points give your answer as a percentage rounded to one decimal placep=%

64.5 %

Step-by-step explanation:

Let's start defining the random variable X.

X : '' SAT critical reading scores from the 2014 school year for high school students in the United States ''

We know that X ~ N (μ,σ)

Where μ is the mean and σ is the standard deviation.

⇒ X ~ N (497,115)

If we want to calculate probabilities related to X we need to standardized the random variable. We do this by subtracting the mean to X and then dividing by the standard deviation. This new random variable will be ''Z'' and Z ~ N (0,1)

We can find the probabilies of ''Z'' in any standard normal table.

The cumulative distribution of ''Z'' is the function Φ where  :

Φ(a)

Now, we need to calculate the following probability :

If we standardized this :

We know that ≅ Z ⇒

⇒

Φ(2.2) - Φ(-0.41) =

⇒ 64.52% ≅ 64.5%

We find that the probability (given as a percentage) is 64.5%

4/6 = 2/3

so it should take 3/3 hours per man. so 9 hours is the answer 3*3 =9

step-by-step explanation:

x = 23.78

step-by-step explanation: