Answer:
Option c. The distributions of weight loss of the two treatments are approximately normally distributed.
Step-by-step explanation:
To increase the confidence level, the results must be able to satisfy the following conditions:
- The sample size is increased. This reduces the margin of the error in the sampling experiment.
- Reduction of the variability. This means that the less the data varies, the more precise the data is.
- Using the one-sided confidence level
- Lowering the confidence level.
All these characteristics can only be satisfied by the normal distribution curve.
Answer:
p
8
Step-by-step explanation:
Answer:
The swimmer must complete the 200-meter backstroke in no more than 130 seconds.
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore 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 pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:

Fastest 6%
At most in the 6th percentile, that is, at most a value of X when Z has a pvalue of 0.07. So we have to find X when Z = -1.555.




The swimmer must complete the 200-meter backstroke in no more than 130 seconds.
1183 rounded to the nearest hundred = 1200
1145 rounded to the nearest hundred = 1100