Answer:
c. (12.12, 18.48)
Step-by-step explanation:
Hello!
The study variable is X: number of times a racehorse is raced during its career.
The average number is X[bar]= 15.3 and the standard deviation is S= 6.8 obtained from a sample of n=20 horses.
To estimate the population mean you need that the variable has a normal distribution, in this case, we have no information about its distribution so I'll assume that it has a normal distribution. With n=20 the most accurate statistic to use for the estimation is a Students-t for one sample, the formula for the interval is:
X[bar] ± 

[15.3 ± 2.093 *
]
[12.12; 18.48]
Using a significance level of 95% you'd expect that the true average of times racehorses are raced during their career is included in the interval [12.12; 18.48].
I hope it helps!
Answer:
A=40, B=60, C=80
Step-by-step explanation:
180/7 to find what "1" would be in the ratio then multiply 20*2, 20*3, 20*4.
It's b because you have to round up
Answer:
11 i think
Step-by-step explanation:
..............
Answer:
<em> x = -3</em>
Step-by-step explanation:
A line has equation: y = ax + b
This line has slope a = 1
This line passes (4, 1)
=> 1 = 4 + b
=> b = -3
=> The equation of this line : y = x - 3
This line passes another point (x, -6)
=> -6 = x - 3
=> x = -6 + 3
=> x = -3