Answer :
Answer:
• (a)X ~ N(16, 5)
,• (b)0.4207
,• (c)19.37 days
Explanation:
(a)
• The mean amount of time = 16 days
,• The standard deviation = 5 days.
Therefore, the distribution of X is:
[tex]X\sim N(16,5)[/tex](b)P(X>17)
To find the required probabability, recall the z-score formula:
[tex]z=\frac{X-\mu}{\sigma}[/tex]When X=17
[tex]z=\frac{17-16}{5}=\frac{1}{5}=0.2[/tex]Next, find the probability, P(x>0.2) from the z-score table:
[tex]P(x>0.2)=0.4207[/tex]The probability that a randomly selected person with a kidney stone will take longer than 17 days to pass it is 0.4207.
(c)The upper quarter is the value under which 75% of data points are found.
The z-score associated with the 75th percentile = 0.674.
We want to find the value of X when z=0.674.
[tex]\begin{gathered} z=\frac{X-\mu}{\sigma} \\ 0.674=\frac{X-16}{5} \\ \text{ Cross multiply} \\ X-16=5\times0.674 \\ X=16+(5\times0.674) \\ X=19.37 \end{gathered}[/tex]The minimum number for the upper quarter of the time to pass a kidney stone is 19.37 days.
