Answer:
c) A matched-pairs t-interval for a population mean difference
Step-by-step explanation:
Matched-Pairs t-Test. A matched-pairs t-test is used to test whether there is a significant mean difference between two sets of paired data.
Answer:
320 yards
Step-by-step explanation:
Alright, there was a lot of addition, and you're just gonna have to trust me, the answer is 320 yards
Answer: 0.0228
Step-by-step explanation:
Given : The mean and the standard deviation of finish times (in minutes) for this event are respectively as :-

If the distribution of finish times is approximately bell-shaped and symmetric, then it must be normally distributed.
Let X be the random variable that represents the finish times for this event.
z score : 

Now, the probability of runners who finish in under 19 minutes by using standard normal distribution table :-

Hence, the approximate proportion of runners who finish in under 19 minutes = 0.0228
2x+5y=619
x=10y-3
________
2(10y-3) +5y=619
20y-6+5y=619
25y=619+6
25y=625
y=625/25
y=25
x=10*25-3
x=250-3
x=247