Answer:
19.875
Step-by-step explanation:
Given that the ,mean is 8000 and the standard deviation is 1000, thus the probability that <span>tube lasts for more than 11000 hours. will be given by:
P(x>11000)
the z-score is:
z=(x-</span>μ<span>)/</span>σ
x=11000
μ=8000
σ=1000
hence:
z=(11000-8000)/1000
z=3
thus
P(x>11000)=1-P(x<11000)
But
P(x<11000)=P(z<3)=0.9987
hence
P(x>11000)=1-0.9987=0.0013
Answer:
89.6
Step-by-step explanation:
(32°C × 9/5) + 32 = 89.6°F
Answer: n = 14
Step-by-step explanation: margin of error = critical value × σ/√n
Where σ = population standard deviation = 1
n = sample size = ?
We are to construct a 99% confidence interval, hence the level of significance is 1%.
The critical value for 2 tailed test at 1% level of significance is gotten from a standard normal distribution table which is 2.58
Margin of error = 0.7
0.7 = 2.58×1/√n
0.7 = 2.58/√n
By cross multipying
0.7×√n = 2.58
By squaring both sides
0.7^2 × n = 2.58^2
0.49 × n = 6.6564
n = 6.6564/0.49
n = 14
Time = distance/velocity = 120/40 = 3 hours
