Solve 7k ÷ 3 = 21.
The solution is k=?

Complete question is;

Scores of an IQ test have a​ bell-shaped distribution with a mean of 100 and a standard deviation of 13. Use the empirical rule to determine the following.

​(a) What percentage of people has an IQ score between 87 and 113​?

​(b) What percentage of people has an IQ score less than 74 or greater than 126​? ​

(c) What percentage of people has an IQ score greater than 139​?

Answer:

A) 68% of the people had an IQ score between 87 and 113

B) 5% of the people had IQ scores less than 74 and greater than 126.

C) 0.15% had an IQ score greater than 139

Step-by-step explanation:

We are given;

Mean; x¯ = 100

Standard deviation; σ = 13

According to the empirical rule in statistics;

>> 68% of the data lies within one standard deviation of the mean

>> 95% of the data lies within two standard deviations of the mean

>> 99.7% of the data lies within three standard deviations

A) We want to find the percentage of people with an IQ score between 87 and 113.

Within one standard deviation, we have;

x¯ ± σ

>> (100 - 13), (100 + 13)

>> (87, 113) which is the range we are looking for.

Thus, 68% of the people had an IQ score between 87 and 113

B) we want to find percentage of people has an IQ score less than 74 or greater than 126.

Let's first find those who had between 74 and 126.

Let's use two standard deviations within the mean.

x¯ ± 2σ

>> (100 - (2×13)), (100 + (2×13))

>> (74, 126) which is the range we are looking for.

So percentage that have IQ scores between 74 and 126 is 95%

Thus;

Percentage of those who had less than 74 and greater than 126 is;

P = 1 - 95%

P = 5%

C) we want to find the percentage of people that had an IQ score greater than 139.

Let's use the z-score formula;

z = (x¯ - μ)/σ

z = (139 - 100)/13

z = 39/13

z = 3

This means it is 3 standard deviations above the mean.

Thus;

Since it's one side outside the mean, then;

Percentage of people with an IQ score greater than 139 = (1 - 99.7%)/2 = 0.3%/2 = 0.15%

Answer:

(2)

Step-by-step explanation:

Let f(x) = y → f-¹(x) = f(y) = x, f(y) is the inverse of f(x)

Thus,

=> -x³ - 9 = y

=> - y - 9 = x³

=> (-y - 9)^(1/3) = x

=> f(y) = x

Inverse is (-y-9)^(1/3)

Replacing the variable, inverse is (-x-9)^(1/3)

Option (2)

Answer:

Experiment.

Step-by-step explanation:

It helps you determine the effect of the medication in a controlled environment with variables and controls.

Answer: 1675 Ft. = Distance from

fire to the windmill.

Step-by-step explanation:

tan8 = 140/X1.

X1 = 140/tan8 = 996.2 Ft.

tan3 = 140/(996+X2)

996+X2 = 140/tan3 = 2671

X2 = 2671-996 = 1675 Ft. = Distance from

fire to windmill.

Step-by-step explanation:

= 2³ + x ³ + 3(2)²x + 3(2)x²

= 8 + x³ + 12x + 6x²

= x³ + 6 x² + 12 x + 8

Answer

3.5 hours

Step-by-step explanation:

Let us represent

The time spent walking as x

The time spent riding as y

Jim began a 146​-mile bicycle trip to build up stamina for a triathlete competition.​ Unfortunately, his bicycle chain​ broke, so he finished the trip walking. The whole trip took 5 hours.

Hence:

x + y = 5.... Equation 1

x = 5 - y

If Jim walks at a rate of 4 miles per hour and rides at 40 miles per​ hour,

The formula for Distance = Speed × time. Hence,

4 × x + 40 × y = 146 miles

4x + 40y = 146.... Equation 2

We substitute 5 - y for x in Equation 2

4(5 - y) + 40y = 146

20 - 4y + 40y = 146

Subtract 20 from both sides

20 - 20 - 4y + 40y = 146 - 20

- 4y + 40y = 146 - 20

36y = 126

y = 126/36

y = 3.5 hours

Since the time he spent raiding his bicycle is represented by "y", the amount of time he spent on the bicycle is 3.5 hours      

I think this is right I had this question I think it was the same one I dont know tho

Answer:

150°

Step-by-step explanation:

35 + 120 + 55 = 210

360 - 210 = 150

Answer:

h(t) = -16t^2+125t

We need to find h(t) when t = 4 s:

h(4) = -16*4^2+125*4

h(4) = 244 ft

The height of the object after 4 seconds is 244 feet.

Answer:

5.357142857

Step-by-step explanation:

Step-by-step explanation:

Continuation of the answer

4x=180 degrees

X=180/4=45 degrees.

Answer:

Im not sure If your suppose to calculate the whole area but for FGH Its 9

Step-by-step explanation:

what are the options?

Answer:

x = -8

Step-by-step explanation:

-3x -6 = 18

-3x = 24

x = -8

Answer:

hi

Step-by-step explanation:

According to the Rational Roots Theorem, the possible rational roots are all the factors of the constant term expressed over the factors of the leading coefficient of the polynomial function. The reason is that the numerator of this rational root is a factor of 4 and the denominator is a factor of 25.

DOES IT HELP?!

Answer: D

Step-by-step explanation: Got it right

Answer:

The confidence interval based on the paired design is wider because there is little variation in mileage between the cars.

Step-by-step explanation:

The sample size randomly collected is matched sample and since the confidence interval is based on the paired design is large and wide. There is small variation between the mileage of the two cars indicating the cars have mileage based on the fuel.

Answer:

1615

Step-by-step explanation:

Area of triangle is: A= B•H•1/2

Area of square is A= L•W

39•17•1/2= 331.5

331.5•4= 1326

17•17= 289

Add the square area to the area of the triangles

289+ 1326= 1615

hope this helps chu <3

Answer:

663

Step-by-step explanation:

Since we are finding the area we multiply Length times Width which is a way of finding formal. L x W so the Length is 17 and Width is 39 so

17 x 39 = 663. So the area is 663

Answer:

80

Step-by-step explanation:

delta math

Answer:

No

No

Yes

Yes

No

Step-by-step explanation:

Answer:

x= $ 7100 investment in first fund

10x+y=84600 substitute the value of x

10*7100+y=84600

y=84600-71000

y= $ 13600 investment in second fund.

Step-by-step explanation:

Answer:

X=2

Step-by-step explanation:

Please mark answer as brainliest

Step-by-step explanation:

for a

x = 11

for b

x = - 3

for c

2 + x = - 5

for d

2x - 1 = 7

Hope it will help :)❤

Step-by-step explanation:

for a

x=-33/3=-11

for b

x=12/-4=-3

for c

2+x=-25/5

2+x=-5

for d

2x-1=-42/-6

2x-1=7

Answer:

a = 19

Step-by-step explanation:

-2(a + 3) = -4a + 32

-2a - 6 = -4a +32

+2a        +2a      

-6 = -2a + 32

-32         -32

-38 = -2a

divide by -2

a = 19

Answer:

a=19

Step-by-step explanation:

-2(a+3) = -4a + 32

-2a - 6 = -4a + 32(Group like terms)

-2a+4a=32+6

2a=38(Divide both sides by 2)

a=19

Answer:

The answer is A

Step-by-step explanation:

Supplementary angles are angles which add up to 180°

∠1 and ∠3 add up to 180°, so they are supplementary.

Answer:

10 years

step-by-step explanation:

First, divide 7.5 by 100, you should get 0.075, then multiply 0.075 by 2000, you should get 150, thats  how much interest he gains each year, now subtract 2000 from 3500 to see how much he needs to get to 3500, you should get 1500, now divide 1500 by 150, you should get 10, which is how many years he will need to get to 3500 from 2000  

Answer:

make dot in the 2,2 8,2 and 5,7 and join the dots

Answer:

a=0

Step-by-step explanation:

first, find the coefficient of 1 (doenst  have to be written)

1+a+1-1=1

remove the opposites

1+a=1

cancel equal terms

a=0