I need help plz help

In a recently administered iq test, the scores were distributed normally, with mean 100 and standard deviation 15. what proporti

iragen [17]

To solve for proportion we make use of the z statistic. The procedure is to solve for the value of the z score and then locate for the proportion using the standard distribution tables. The formula for z score is:

z = (X – μ) / σ

where X is the sample value, μ is the mean value and σ is the standard deviation

when X = 70

z1 = (70 – 100) / 15 = -2

Using the standard distribution tables, proportion is P1 = 0.0228

when X = 130

z2 = (130 – 100) /15 = 2

Using the standard distribution tables, proportion is P2 = 0.9772

Therefore the proportion between X of 70 and 130 is:

P (70<X<130) = P2 – P1

P (70<X<130) = 0.9772 - 0.0228

P (70<X<130) = 0.9544

Therefore 0.9544 or 95.44% of the test takers scored between 70 and 130.

6 0

3 years ago

Let f(x)=x^2f ( x ) = x 2. Find the Riemann sum for ff on the interval [0,2][ 0 , 2 ], using 4 subintervals of equal width and t

sladkih [1.3K]

Answer:

$A_L=1.75$

Step-by-step explanation:

We are given:

$f(x)=x^2$

$interval = [a,b] = [0,2]$

Since $n = 4$ ⇒ $\Delta x = \frac{b-a}{n} = \frac{2-0}{4}=\frac{1}{2}$

Riemann sum is area under the function given. And it is asked to find Riemann sum for the left endpoint.

$A_L= \sum\limits^{n}_{i=1}\Delta xf(x_i) = \frac{1}{2}(0^2+(\frac{1}{2})^2+1^2+(\frac{3}{2})^2)=\frac{7}{4}=1.75$

Note:

If it will be asked to find right endpoint too,

$A_R=\sum\limits^{n}_{i=1}\Delta xf(x_i) =\frac{1}{2}((\frac{1}{2})^2+1^2+(\frac{3}{2})^2+2^2)=\frac{15}{4}=3.75$

The average of left and right endpoint Riemann sums will give approximate result of the area under $f(x)=x^2$ and it can be compared with the result of integral of the same function in the interval given.

So, $(A_R+A_L)/2 = (1.75+3.75)/2=2.25$

$\int^2_0x^2dx=x^3/3|^2_0=8/3=2.67$

Result are close but not same, since one is approximate and one is exact; however, by increasing sample rates (subintervals), closer result to the exact value can be found.

3 0

3 years ago

What is an equation in point-slope form of the line shown in the graph,using the point (-2,-1)

mylen [45]

Y+1=[m(the slope)](x+2), y=mx+2m-1, it is impossible to get the answer without the graph.

7 0

3 years ago

List the information as ordered pairs (weeks, total dollars saved).

morpeh [17]

Marcus
Weeks Total Saved (x, y)
1 10 (1,10)
2 20   (2, 20)
3   30   (3 30)
4   40   (4, 40)

David
Weeks Total Saved (x, y)
1 15 (1, 15)
2 30   (2, 30)
3 45   (3, 45)
4 60   (4, 60)

8 0

3 years ago

The largest jaw breaker in a store is spherical with a radius of 2 in. and sells for $4.00. A

Dennis_Churaev [7]

Answer:

$12

Step-by-step explanation:

Given data

Radius= 2in

cost = $4

New jaw breaker radius= 6in

cost=???

If 2 in jaw breaker cost $4

6in jaw breaker will cost x

cross multiply

6*4= 2*x

24= 2x

x= 24/2

x= $12

Hence the 6 in jawbreaker will cost $12

3 0

2 years ago