English translation:
If the quality control manager wants to estimate the average life of lamps with 20 hours, with a confidence level of 95% and an error of 10% is assumed. What is the sample size?
The answer is 4. The mean is 4 beacuse thats what you multiply ... and yeah
Answer:
proper because the numerator is lower than the denominator
We can simply observe that.
- 0.777... is rational, because it is a number with infinite but repeating decimal part.
- 1/3 is rational, because it's the division between two integers
, so this is rational as well.
Since the product of two rational numbers is always rational, we have that

are all rationals, since they are the product of two rationals.
On the other hand, we have

and thus

which is irrational.