1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Galina-37 [17]
3 years ago
5

The completion time for an exam is normally distributed with expected value 75 minutes and variance 12 minutes. What is the prob

ability that a student will finish this exam in less than 70 minutes or more than 80 minutes?
Mathematics
1 answer:
Debora [2.8K]3 years ago
5 0

Answer:

14.89% or 0.1489

Step-by-step explanation:

First, find the z-score for both 70 and 80 minutes and their corresponding percentile.

z= \frac{X - \mu }{SD} \\SD=\sqrt{V} =\sqrt{12}\\\mu =75\\z= \frac{X - 75}{\sqrt{12}}\\\\

For X = 70 minutes:

z= \frac{70 - 75}{\sqrt{12}}\\z=-1.4434

This z-score is equivalent to the 7.445 th percentile, so the probability of a student finishing this exam in less than 70 minutes is 7.445%

or X = 80 minutes:

z= \frac{80 - 75}{\sqrt{12}}\\z=1.4434

This z-score is equivalent to the 92.555 th percentile, so the probability of a student finishing this exam in more than 80 minutes is 100- 92.555 = 7.445%

Therefore, the probability (P) of a student finishing this exam in less than 70 minutes or more than 80 minutes is:

P = 7.445% + 7.445% = 14.89%

You might be interested in
[-1 + (-4)] + (6/7 + 1/7)
Radda [10]

Answer:-4

Step-by-step explanation:

-1 +-4 is -5 and 6/7 + 1/7 =1 so -5 +1=-4

4 0
3 years ago
Amber put gasoline into her car she wrote down that she added 56.78 liters of gas but she rounded the amount to the nearest hund
Trava [24]

Answer:

56.779 or 56.782 56.778, etc, because it has to be 8 in the hundreths thousandths less than 5 or 7 in the hundreths thousandths greater than 5

7 0
2 years ago
The terminal side of an angle in standard position passes through p(–3, –4). what is the value of tangent theta?
astraxan [27]

Answer:

  4/3

Step-by-step explanation:

The tangent of any angle (θ) in standard position that has point (x, y) on its terminal ray is ...

  tan(θ) = y/x

__

For the given point on the terminal side, the tangent is ...

  tan(θ) = (-4)/(-3) = 4/3

_____

<em>Additional comment</em>

There are several ways this can be explained. One of them makes use of the relation between rectangular and polar coordinates:

  (x, y) = (r·cos(θ), r·sin(θ))

Then the ratio y/x is ...

  y/x = (r·sin(θ))/(r·cos(θ)) = sin(θ)/cos(θ) = tan(θ)

6 0
1 year ago
Read 2 more answers
How many square feet of outdoor carpet will we need for this hole​
DIA [1.3K]

Answer:

39ft²

Step-by-step explanation:

Divide up the Shape

Big rectangle:

a=lw

11*3=33ft

Small rectangle

2*3=6ft

Whole shape:

33+6=39ft²

4 0
2 years ago
Why is the answer A? Plzzz explain.
Contact [7]

Answer:


Step-by-step explanation:

f(x) = x^2 + 4x + 4

f(x + a) = (x + a)^2 + 4(x + a) + 4

f(x + a) = x^2 + 2ax + a^2 + 4x + 4a + 4   Now combine like terms and use the distributive property.

f(x + a) = x^2 + (2a + 4)x + a^2 + 4a + 4

We are told that f(x + a) = x^2 - 6x + 9

So that means that

2a + 4 = - 6      Subtract 4 from both sides.

2a = - 6 - 4

2a = - 10          Divide by 2

a = - 10/2

a = - 5.            

But you are not finished. You have to check the last part.

a^2 + 4x + 4 = 9

(a + 2)^2 = 9

Take the square root of both sides

sqrt(a+ 2)^2 = +/- 3

a+2 = 3

a = 1.

Does this work or is it extraneous? It is extraneous because it will not work for  2(a) + 4 = - 6  

You get 6 = - 6 which is not correct. But you did give the second best answer.

a + 2 = - 3

a = - 3 - 2

a = - 5 which agrees with your previous answer.

===========

This is an extremely hard or tricky or sneaky problem. It takes a lot of conniving to get the right answer and 1 is not a left field answer. It just does not happen to be correct.

8 0
3 years ago
Other questions:
  • Are all isosceles triangles equilateral<br>??​
    7·1 answer
  • find a number such that if you add 8 and divide the result by 4 you will get the same answer as if you subtracted 3 from the ori
    15·1 answer
  • a block has two red sides, two green sides, one blue side and one yellow side what is the probability that when the block is rol
    13·2 answers
  • 2. What is the solution to this equation?<br> 2 x + 3 = x - 4
    12·2 answers
  • If the Math Olympiad Club consists of 18 students, how many different teams of 3 students can be formed for competitions?
    10·2 answers
  • What positive or negative integer represents you descending 15 feet into a cave?
    8·1 answer
  • PLs help lots of points
    6·2 answers
  • Write the following number in scientific notation: .00098
    5·1 answer
  • What is the correct answer?
    15·2 answers
  • Solve: log8 (x - 4) = 2
    9·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!