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
posledela
2 years ago
12

Scores on a final exam taken by 1200 students have a bell shaped distribution with mean=72 and standard deviation=9

Mathematics
1 answer:
SVETLANKA909090 [29]2 years ago
8 0

Answer:

a. 72

b. 816

c. 570

d. 30

Step-by-step explanation:

Given the graph is a bell - shaped curve. So, we understand that this is a normal distribution and that the bell - shaped curve is a symmetric curve.

Please refer the figure for a better understanding.

a. In a normal distribution, Mean = Median = Mode

Therefore, Median = Mean = 72

b. We have to know that 68% of the values are within the first standard deviation of the mean.

i.e., 68% values are between Mean $ \pm $ Standard Deviation (SD).

Scores between 63 and 81 :

Note that 72 - 9 = 63 and

72 + 9 = 81

This implies scores between 63 and 81 constitute 68% of the values, 34% each, since the curve is symmetric.

Now, Scores between 63 and 81 = $ \frac{68}{100} \times 1200 $

= 68 X 12 = 816.

That means 816 students have scored between 63 and 81.

c. We have to know that 95% of the values lie between second Standard Deviation of the mean.

i.e., 95% values are between Mean $ \pm $ 2(SD).

Note that 90 = 72 + 2(9) = 72 + 18

Also, 54 = 63 - 18.

Scores between 54 and 90 totally constitute 95% of the values. So, Scores between 72 and 90 should amount to $ \frac{95}{2} \% $ of the values.

Therefore, Scores between 72 and 90 = $ \frac{95}{2(100)} \times 1200 = \frac{95}{200} \times 1200  $

$ \implies 95 \times 12 $ = 570.

That is a total of 570 students scored between 72 and 90.

d. We have to know that 5 % of the values lie on the thirst standard Deviation of the mean.

In this case, 5 % of the values lie between below 54 and above 90.

Since, we are asked to find scores below 54. It should be 2.5% of the values.

So, Scores below 54 = $ \frac{2.5}{100} \times 1200 $

= 2.5 X 12 = 30.

That is, 30 students have scored below 54.

You might be interested in
Does anyone know where this worksheet is at on online with the answers ?
Vlad1618 [11]

Answer:

I do not know if there is this worksheet online which comes with answers, but you can post questions here on brainly, and I can help you clarify them!!

:>>

8 0
2 years ago
1. Water is filling a bathtub at a rate of 7 gallons per minute. Complete the table of equivalent
ASHA 777 [7]

Answer:

amount of water: 7, 14, 21, 28, 35

time : 1,2,3,4,5

6 0
3 years ago
Q # 20 please help to solve
spin [16.1K]
If submarine is at the surface (the initial position) and then dives 375 ft, the coordinate  of submarine becomes -375 ft <span>relatively to the initial position. When the submarine dives another 175 ft down, the coordinate of submarine becomes -375-175=-550 ft relatively to the initial position.
</span>
Answer: Correct choice is A.
<span />
8 0
3 years ago
Which expression is equivalent to 6 – (–8)?<br> –6 + 8<br> –6 + –8<br> 6 + –8<br> 6 + 8
Jet001 [13]
I think that the answer would be 6+-8 because it equals -2 and 6-(-8)= -2
8 0
3 years ago
Which expression equals 102+84
MakcuM [25]

Answer: 6(17+14) or 186

Step-by-step explanation: I provide with you two answers since not sure what u  mean .And the first answer is distributive it and the second answer is the sum.

Also 102 + 84 is an expression already so I don't know what your asking and if this help  u are welcome !

4 0
2 years ago
Other questions:
  • Equation Help For Thank You​
    15·1 answer
  • Andre and Morgan are both headed to Florida for vacation. Andre will drive 70 miles per hour. Morgan will drive 55 miles per hou
    11·1 answer
  • If a bicyclist is traveling at a speed of 10 km/h, he will be late by 1 hour. If he will travel at a speed of 15 km/h, then he w
    13·1 answer
  • You've dropped your car keys at night off the end of a dock into water 1.6 m deep. a flashlight held directly above the dock edg
    12·1 answer
  • What is the greatest common factor of 28 and 96
    14·2 answers
  • What is the simplified answer?<br> 13x + 6 - 8x -2
    8·2 answers
  • Jefferson middle school students were asked which sports are the coming year 26 students in basketball and eight sports a total
    6·1 answer
  • If the sum of interior angle is 3780 degree.find the number of sides
    14·2 answers
  • What is the volume of the oblique cylinder rounded to the nearest cm^3?
    14·1 answer
  • (4 x 10) + (2 x 104)<br> Give your answer in standard form
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!