Let X be the national sat score. X follows normal distribution with mean μ =1028, standard deviation σ = 92
The 90th percentile score is nothing but the x value for which area below x is 90%.
To find 90th percentile we will find find z score such that probability below z is 0.9
P(Z <z) = 0.9
Using excel function to find z score corresponding to probability 0.9 is
z = NORM.S.INV(0.9) = 1.28
z =1.28
Now convert z score into x value using the formula
x = z *σ + μ
x = 1.28 * 92 + 1028
x = 1145.76
The 90th percentile score value is 1145.76
The probability that randomly selected score exceeds 1200 is
P(X > 1200)
Z score corresponding to x=1200 is
z = 
z = 
z = 1.8695 ~ 1.87
P(Z > 1.87 ) = 1 - P(Z < 1.87)
Using z-score table to find probability z < 1.87
P(Z < 1.87) = 0.9693
P(Z > 1.87) = 1 - 0.9693
P(Z > 1.87) = 0.0307
The probability that a randomly selected score exceeds 1200 is 0.0307
Answer:
2y - 15
Step-by-step explanation:
well 15 LESS than TWICE a number. okay so let’s start off by making a variable for the unknown number.... y. the variable is y. so now we have to think, TWICE that number, but we don’t know the number.
Now that we have the variable and we know it has to be doubled, let’s start off making the first half... we can out that into 2y. which is 2 multiplied by the unknown number.
now that we have the first half done, we have to take the 15 less. Less can mean or subtract in this kind of situation. but for this certain scenario, it will be subtraction. so the equation would be 2y - 15.
Step-by-step explanation:
Given :-
The length of the garden 8m greater than 2 times the width.
Area of the garden is 280 m²
Let us consider the length as x and width as y.
Sp, we can day length as :-
x = 8 + 2y ---(1)
Now, we know that:-
Area of Rectangle = Length × Breadth
280 = x * y
We can replace the value of x now,
280 = y × ( 8 + 2y)
280 = 8y + 2y²
2y² + 8y - 280 = 0
y² + 4y - 140 = 0
Factorise it.
(y -10)(y + 14)
Cancelling -ve value, we get the width as 10 metres.
<u>Hope</u><u> </u><u>it</u><u> </u><u>helps</u><u> </u><u>:</u><u>)</u>
Answer:
-600
Step-by-step explanation:
The rate of change of a function f(x) in a certain interval
is the ratio between the change of the function and the change in the value of x:

The rate of change of a function tells how much the value of the function is changing per change in unit of x: therefore, for a linear function it corresponds to the slope of the line.
In this problem, the function f(x) is equal to the value of the business machine in dollars, while the variable x represents the number of years.
Here we are told that the machine was purchased for

while its value decreases by $600 each year, so

This means that the linear function that represents the value of the machine after x years is:

Therefore, the rate of change of the function is -600.