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svet-max [94.6K]
2 years ago
9

The lengths of text messages are normally distributed with a population standard deviation of 3 characters and an unknown popula

tion mean. If a random sample of 24 text messages i taken and results in a sample mean of 27 characters, find a 99% confidence interval for the population mean. Zo.10Z0.0520.025 Zo.01 Z0.005 1.282 1.645 1.960 2.326 2.576 You may use a calculator or the common z values above. Select the correct answer below: a.(26.21,27.79) b.(25.99.28.01) c.(25.93,28.07)
Mathematics
1 answer:
slava [35]2 years ago
5 0

Answer:

25.4, 28.6

Step-by-step explanation:

Given parameters

sample size, n = 24

sample mean, X = 27

population standard deviation, s = 3

critical value, Zα/2, where α = 0.01

99% confidence Interval, CI, is given as follows

CI = X ± Zα/2 × (s/√n)

Zα/2 = Z0.01/2 = Z0.005 = 2.576

CI = 27 ± 2.576 × (3/√24)

   = (25.42 ,28.57)

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3 0
2 years ago
A small company that manufactures snowboards uses the relation below to model its profit. In the model,
amm1812

Answer:

a)   x₁ = 14

     x₂ = - 6

b) x = 4

c) P(max ) = 4000000 $

Step-by-step explanation:

To find the axis of symmetry we solve the equation

a) -4x² + 32x + 336 = 0

4x²  - 32x  - 336  = 0       or    x² - 8x - 84 = 0

x₁,₂ = [ -b ± √b² -4ac ]/2a

x₁,₂ = [ 8  ±√(64) + 336 ]/2

x₁,₂ = [ 8  ± √400 ]/2

x₁,₂ =( 8 ± 20 )/2

x₁  = 14

x₂ = -6

a) Axis of symmetry must go through the middle point between the roots

x = 4 is the axis of symmetry

c) P = -4x² + 32x + 336

Taking derivatives on both sides of the equation we get

P´(x) = - 8x + 32  ⇒  P´(x) = 0     - 8x + 32

x = 32/8

x = 4    Company has to sell  4 ( 4000 snowboard)

to get  a profit :

P = - 4*(4)² + 32*(4) + 336

P(max) = -64  + 128 + 336

P(max) = 400           or  400* 10000 =  4000000

     

8 0
3 years ago
Algebraic 3 more than 5 times a number
artcher [175]

Answer:

5x+3

Step-by-step explanation:

substitute x for the unknown number

8 0
3 years ago
Please answer fast, this is urgent no explanation need just list answer 1,2,3etc. thanks :)
Sav [38]

Answer:

Hi There!

Step-by-step explanation:

Your Answers Are:

<h3>1: 19.3 CM</h3><h3>2: 273 CM</h3><h3>3: about 45-65 degrees</h3><h3>4: 15 CM</h3><h3>5: 25 CM</h3><h3 /><h3 />

Its hard to work w/o a ruler or a protractor, so these might be incorrect.

If this helps, though, please give me a thanks!! ^^

- abakugosimp

5 0
2 years ago
143+ [(96 + 8) 5] – 42.
Tresset [83]

Answer:

621

Explanation:

143 + (96 + 8)(5) − 42

(96 + 8)(5)

= 520

143 + 520 - 42

= 663

663 - 42

= 621

7 0
3 years ago
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