Answer:
e. All of the reasons are correct.
Step-by-step explanation:
In most cases, studying all the population is impossible. In other cases, it is too expensive or time consuming.
A sample will give us, in most cases and combined with tools of statistical analysis (hypothesis testing or confidence intervals), enough information to make an unbiased estimation about the characteristic of the population we are studying.
Answer:
0.8413 = 84.13% probability of a bulb lasting for at most 605 hours.
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the z-score of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
The standard deviation of the lifetime is 15 hours and the mean lifetime of a bulb is 590 hours.
This means that 
Find the probability of a bulb lasting for at most 605 hours.
This is the pvalue of Z when X = 605. So



has a pvalue of 0.8413
0.8413 = 84.13% probability of a bulb lasting for at most 605 hours.
f(x) = x2 - x + 2
f(-1)=(-1)²-(-1)+2=4 contain the point (-1,4)
f(0) = 0²-0+2 = 2 contain the point (0,2)
f(2) = 2²-2+2 =4 contain the point (2,4)
Answer:
974
Step-by-step explanation:
(91.01)*(10.7)
91.01*(10.7)
91.01*10.7
973.80700
974