225,621 views
2 votes
2 votes
I can find percentages and values using the 68-95-99.7 rule, z-scores, and the standard normal distribution.only answer please if you know the answer

I can find percentages and values using the 68-95-99.7 rule, z-scores, and the standard-example-1
User Benjy Wiener
by
3.8k points

1 Answer

0 votes
0 votes

Let X be the weight of fish in the lake.

Given that the mean and standard deviation as 20 and 6 respectively,


\begin{gathered} \mu=20 \\ \sigma=6 \end{gathered}

Consider the formula,


z=(x-\mu)/(\sigma)

The proportion of fish weighing less than 15 pounds is calculated as,


\begin{gathered} P(X<15)=P(z<(15-20)/(6)) \\ P(X<15)=P(z<-0.83) \\ P(X<15)=P(z<0)-P(-0.83From the Standard Normal Distribution Table,[tex]\emptyset(-0.83)=0.2967

Substitute the value,


\begin{gathered} P(X<15)=0.5-0.2967 \\ P(X<15)=0.2033 \end{gathered}

Mulyiply by 100 to get the equivalent percent,


P(X<15)=20.33\text{ percent}

Thus, 20.33% of fish in the lake will weigh less than 15 pounds.

User Peterlandis
by
3.5k points