Answer:
Chain referral sampling
Step-by-step explanation:
Chain referral sampling is also known as snowball sampling. In this form of sampling, the samples are collected from the referrals given by the existing samples. The samples are collected and the research is conducted respectively. This method is used in the business marketing also. The places where the people are not known by the company, the method of chain referrals are made and the samples are collected.
Using a system of equations, it is found that David is 12 years old.
<h3>What is a system of equations?</h3>
A system of equations is when two or more variables are related, and equations are built to find the values of each variable.
The variables are given as follows:
- Variable z: Rebecca's age.
David is three times younger than the dad and twice as old as Rebecca, then:
Rebecca is 30 years younger than the dad, hence:
z = y - 30.
Then, since x = 2z and z = y - 30 and y = 3x, we solve for x to find David's age.
x = 2(y - 30)
x = 2(3x - 30)
x = 6x - 60
5x = 60
x = 60/5
x = 12.
David is 12 years old.
More can be learned about a system of equations at brainly.com/question/24342899
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Answer:
0.18 sec or 3.4 sec.
For second part, it will take 3.7 sec.
First part:
Set h(t) = 17and solve for t.
-16t²+ 58t + 7= 17
-16t² + 58t - 10 = 0
Solve this quadratic equation for t. You should get 2 positive solutions. The lower value is the time to reach 17 on the way up, and the higher value is the time to reach 17 again, on the way down.
Second part:
Set h(t) = 0 and solve the resulting quadratic equation for t. You should get a negative solution (which you can discard), and a positive solution. The latter is your answer.
