The probability that a randomly selected runner has a time less than or equal to 3 hours and 20 minutes is 0.16 or 16%.
<h3>What is normally distributed data?</h3>
Normally distributed data is the distribution of probability which is symmetric about the mean.
The mean of the data is the average value of the given data.
The standard deviation of the data is the half of the difference of the highest value and mean of the data set.
The times of the runners in a marathon are normally distributed, with
- Mean of 3 hours and 50 minutes
- Standard deviation of 30 minutes.
Refere the probabiliity table attached below. The probability of Z being inside the 1 Standard daviation of mean is 0.84.
The probability of runner selected with time less than or equal to 3 hours and 20 minutes,
Thus, the probability that a randomly selected runner has a time less than or equal to 3 hours and 20 minutes is 0.16 or 16%.
Learn more about the normally distributed data here;
brainly.com/question/6587992
3x² - 5x6
= 3x² - 30
if u then have to simplify it, the answer would be
3(x²-10)
We're measuring a quantity of pure detergent.
We start with 11 gallons of an 18% solution. 18% of that, or 1.98 gallons, is pure detergent, and the rest of these 11 gal. is water: 9.02 gal. We will add x gallons of water to this solution to obtain (11+x) gallons of a 12% solution.
We need to find x to satisfy this equation:
(11 gallons + x)(0.12) = (11 gallons)(0.18)
Div. both sides by 0.12, we get (11 gallons + x) = (11 gallons)(1.5)
Mult. both sides by 10, we get 110 gallons + 10x = (11 gallons)(15)
Then 10x = 165 gallons - 110 gallons, or 55 gallons.
Div. both sides by 10, we get x = 5.5 gallons (answer)