Answer:
Pythagorean theorem, eh?
Step-by-step explanation:
The way to do this is use the radius-tangent angle theorem thing...
It states that, a radius that intersects a point of tangency(I think that's what it's called) is perpendicular to the tangent. Thus, CW is perpendicular to OW!
Thus, it forms a right triangle, where we can use Pythagorean Theorem!
If you don't know what it is, check the internet! It's pretty simple.

So, there you go! Hope this helps!
NOTE: This answer was recently deleted for violating community guidelines, so I just re-uploaded it!(and edited it) So if you do need more help, do some research!
90 minutes or 1 hour and 30 minutes.
Hope this helps,
kwrob
The answer to this is 39 and 27
Answer:
Step-by-step explanation:
We want to determine a 95% confidence interval for the population mean.
Number of sample, n = 56
Mean, u = 645 hours
Standard deviation, s = 31 hours
For a confidence level of 95%, the corresponding z value is 1.96.
We will apply the formula
Confidence interval
= mean ± z ×standard deviation/√n
It becomes
645 ± 1.96 × 31/√56
= 645 ± 1.96 × 4.142
= 645 ± 8.12
The lower end of the confidence interval is 645 - 8.12 =636.88
The upper end of the confidence interval is 645 + 8.12 =653.12
Therefore, with 95% confidence interval for the population mean life of fluorescent light bulbs is between 636.88 hours and 653.12 hours