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
Harrizon [31]
3 years ago
12

Suppose that 12% of test scores for the unit 1 test were above 85 and 8% were below 70. Assuming a normal

Mathematics
1 answer:
Doss [256]3 years ago
4 0

Answer:

Mean = 78.2

Standard deviation = 5.8

Step-by-step explanation:

Mathematically z-score;

= (x-mean)/SD

From the question;

12% of test scores were above 85

Thus;

P( x > 85) = 12%

P(x > 85) = 0.12

Now let’s get the z-score that has a probability of 0.12

This can be obtained from the standard normal distribution table and it is = 1.175

Thus;

1.175 = (85 - mean)/SD

let’s call the mean a and the SD b

1.175 = (85-a)/b

1.175b = 85 - a

a = 85 - 1.175b ••••••••(i)

Secondly 8% of scores were below 70

Let’s find the z-score corresponding to this proportion;

We use the standard normal distribution table as usual;

P( x < 70) = 0.08

z-score = -1.405

Thus;

-1.405 =( 70-a)/b

-1.405b = 70-a

a = 70 + 1.405b ••••••(ii)

Equate the two a

70 + 1.405b = 85 - 1.175b

85 -70 = 1.405b + 1.175b

15 = 2.58b

b = 15/2.58

b = 5.81

a = 70 + 1.405b

a = 70 + 1.405(5.81)

a = 78.16

So mean = 78.2 and Standard deviation is 5.8

You might be interested in
Will some one please help me :)
Jobisdone [24]
Ummm let’s see.. yah I have no clue sorry buddy your just gonna have to get this one wrong
7 0
3 years ago
15 points!!!:
spin [16.1K]
If you’re both working at a constant rate, then he would have one hour left when you go to help him. Since there are two of you, you accomplish the task twice as fast, in 30 minutes
6 0
3 years ago
Dylan bought 3 identical shirts online for a total cost of $71.83 including a flat rate of $7.99 for shipping. Drag numbers to c
Vesnalui [34]

Answer:

3s + 7.99 = 71.83

Step-by-step explanation:

Yeah, algebra sure confused me the first time I took it. I had a much more patient and engaging teacher the second time!

How would we find out in real life how much each shirt cost? We'd subtract 7.99 from 71.83 and divide the difference by 3, right??

Let's work that backward. Let's say a shirt cost $6. Three would cost $3(6), or $18. Since each shirt costs $s, our price for 3 shirts is $3s. We have to add shipping to get a total, which we are given. When writing an equation, we leave out labels like $ or meters or books or whatever.

3 0
3 years ago
Pleas please help me with my math problem! Thank You :)
dalvyx [7]

Check the picture below.

as you recall from the previous exercise, x = 74°, now, using the "inscribed angle theorem" as you saw already, the green intercepted arc is 160°, so y = 160° - 74°.

as far as ∡z, well, we can just use the "inscribed quadrilateral conjecture".

3 0
3 years ago
1:01+0.25.4+32=<br><br>help 10 points​
tia_tia [17]

Answer:

55 39

Step-by-step explanation:

7 0
3 years ago
Other questions:
  • Simplify 3(2x-7y)+2(2x+3)=
    8·1 answer
  • Suzette went to the mall with her uncle Louie and ended up having to borrow some money to finish her holiday shopping. Suzette s
    13·1 answer
  • What is the answer ?
    12·1 answer
  • Multiply<br>8(-12)<br>what is the answer​
    15·2 answers
  • Solving by elimination
    14·1 answer
  • Can anyone solve this ?
    13·1 answer
  • Find the domain of the following functions?
    5·1 answer
  • Plz help help❤️Urgently
    6·1 answer
  • What is the range of f (x)=3 ^ x?
    15·1 answer
  • Use the line plot to answer the question.
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!