Answer: a) (1008.34,1019.658) b) (1009.24,1018.76)
Step-by-step explanation:
Since we have given that
n = 75
mean = 1014 hours
Standard deviation = 25 hours
At 95% two sided , z = 1.96
So, confidence interval would be
(b) Construct a 95% lower confidence bound on the mean life.
z = 1.65
So, confidence interval would be
Hence, a) (1008.34,1019.658) b) (1009.24,1018.76)
Answer 2. You just have to find wants similar and put it out front and then leave wants left in parentheses
145-13-9-5 that what your looking for
There's a really easy way to convert any units to other units.
Right now, we have the fraction (4 miles) / (2 hours).
We want to find a fraction that's exactly equal to that one,
but has the units of (miles/minute) or maybe (feet/minute).
Just take the original fraction, and multiply it by some other
fractions.
Each fraction you multiply it by must have the value of ' 1 ' so
you don't change the value of the original fraction. But it can
have different units, that cancel with other units to eventually
give you the units you want.
(4 miles / 2 hours) times (1 hour / 60 minutes)
The second fraction is equal to ' 1 ', because the top and the bottom
have the same value ... 1 hour is the same thing as 60 minutes.
Multiply the fractions: (4 miles x 1 hour) / (2 hour x 60 minutes)
Now you can cancel 'hour' from the top and the bottom, and you have
(4 miles x 1) / (2 x 60 minutes)
= (4 miles) / (120 minutes)
= (4 / 120) mile/minute = 0.0333... mile / minute .
Let's do it again, go a little farther, and get an answer that
might mean more and feel more like an answer.
(4 miles) / (2 hours) x (5280 feet / mile) x (1 hour / 60 minutes)
The 2nd and 3rd fractions both have the value of ' 1 ', because
the top is equal to the bottom.
Multiply all three fractions:
(4 miles x 5280 feet x 1 hour) / (2 hours x 1 mile x 60 minutes)
You can cancel both 'mile' and 'hour' out of the top and bottom,
and look what you have left:
(4 x 5280 feet x 1) / (2 x 1 x 60 minutes)
= (4 x 5280) / (2 x 60) feet / minutes
= (21,120 / 120) feet/minute = 176 feet per minute
