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
natka813 [3]
3 years ago
5

The mean life of a particular brand of light bulb is 1200 hours. if you know that at about 95% of this brand of bulbs will last

between 800 and 1600 hours, then what is the standard deviation of the light bulbs' life?
Mathematics
1 answer:
Snowcat [4.5K]3 years ago
4 0
<span>204
   First, lookup a standard normal table and see what the z-score is for 0.025 (one half of 100% - 95%) to allow for equal sized tails. You should find that the z-score is 1.96. That means that 95% of the time, the value should be within 1.96 standard deviations of the mean. Now let's calculate the standard deviation. 800 is 800 - 1200 = -400 to the left of the mean of 1200. 1600 is 1600 - 1200 = 400 to the right of the mean of 1200. So we are an equal distance of 400 on both sides of the mean. And we know from the z-score of 1.96, that we're 1.96 standard deviations from the mean. So a little division will give us the standard deviation. Which is: 400 / 1.96 = 204.0816327
   So the standard deviation of the light bulbs is 204</span>
You might be interested in
FIND M∠R (GIVING BRAINLIEST, 25 PTS)
riadik2000 [5.3K]

Answer:

<h2>76</h2>

Step-by-step explanation:

<h3>to understand this</h3><h3>you need to know about:</h3>
  • triangles
  • equation
  • PEMDAS
<h3>given:</h3>
  • M\angle T=2x+2
  • M\angle R=3x+1
<h3>tips and formulas:</h3>
  • this is an isosceles triangle since two sides are equal therefore \angle T=\angle S
  • a triangle contains 180°
<h3>let's solve:</h3>

according to the question

2x+2+2x+2+3x+1=180

solve:

  1. collect like terms:7x+5=180
  2. substract 5 from both sides:=>7x+5-5=180-5=>7x=175
  3. divide both sides by 7: =>7x/7=175/7
  • x=25

given:

M∠R=3x+1

substitute the value of x

3×25+1

75+1

76

7 0
2 years ago
Read 2 more answers
Assume the probability of having a boy or a girl is the same. What is the probability a family has three boys?
almond37 [142]
The probability of having a boy: 1/2

1/2(1/2)(1/2)=1/8

The probability of a family having three boys is 1/8.

Hope this helps!
3 0
3 years ago
During a film festival, the first film ticket is priced at $16, and each additional ticket is $11. If Rico spends $71, then how
Nina [5.8K]

Answer:

5

Step-by-step explanation:

16 + 11x = 71

16 + -16 + 11x = 71 + -16

16 + -16 = 0

0 + 11x = 71 + -16

11x = 71 + -16

11x = 55

x = 5

6 0
3 years ago
Which whole-number values of x make the inequality 3x -2 &lt; 12 true?
Rufina [12.5K]
3x - 2 < 12
3x < 12 + 2
3x < 14
x < 14/3
x < 4 2/3......whole-number value = 4
4 0
3 years ago
A teacher gave her class two exams; 60% of the class passed the second exam, but only 48% of the class passed both exams. What p
Free_Kalibri [48]
Should be 
0.48 / 0.60 = 0.80 = 80%

answer
80% <span>passed the second exam also passed the first exam</span>
4 0
3 years ago
Read 2 more answers
Other questions:
  • PLEASE HELP!!!!!!!!!!!!!!!
    9·1 answer
  • What is the percent change from 20 to 35
    9·2 answers
  • What is the value of y in the equation 4y – 2(1 – y) = –44?
    12·1 answer
  • What is the measure of each interior angle of a regular 16-gon?
    6·1 answer
  • -4<img src="https://tex.z-dn.net/?f=%5Cgeq" id="TexFormula1" title="\geq" alt="\geq" align="absmiddle" class="latex-formula">4(6
    10·1 answer
  • What is tje value of 9 and 10
    7·1 answer
  • True or False: The FOIL method is an example of the distributive<br> property.
    9·2 answers
  • X=20 is the solution to 4=x-16
    15·1 answer
  • A cell reproduces by doubling every hour. If you start with a single cell, how many will you have in 24 hours?
    8·2 answers
  • I need help with 1 and 2
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!