Answer:
Step-by-step explanation:
Hello!
To test if boys are better in math classes than girls two random samples were taken:
Sample 1
X₁: score of a boy in calculus
n₁= 15
X[bar]₁= 82.3%
S₁= 5.6%
Sample 2
X₂: Score in the calculus of a girl
n₂= 12
X[bar]₂= 81.2%
S₂= 6.7%
To estimate per CI the difference between the mean percentage that boys obtained in calculus and the mean percentage that girls obtained in calculus, you need that both variables of interest come from normal populations.
To be able to use a pooled variance t-test you have to also assume that the population variances, although unknown, are equal.
Then you can calculate the interval as:
[(X[bar]_1-X[bar_2) ±
*
]


[(82.3-81.2) ± 1.708* (6.11*
]
[-2.94; 5.14]
Using a 90% confidence level you'd expect the interval [-2.94; 5.14] to contain the true value of the difference between the average percentage obtained in calculus by boys and the average percentage obtained in calculus by girls.
I hope this helps!
Answer:
the factored form is -5x^2(7x-1)
The kids have to wait for 1 hour to get their bags.
<u>Step-by-step explanation:</u>
Given that,
A bus with kids and a truck with their bags started moving from the school to the camp at the same time.
- The speed of the bus was 60 mph.
- It took kids 3 hours to reach the camp.
<u>To find the distance traveled by the bus :</u>
⇒ Distance = Speed × Time
⇒ 60 × 3
⇒ 180 m
∴ The distance is 180 m.
<u>To find the time taken by the truck to reach the camp :</u>
- The speed of the truck was 45 mph.
- We found the distance as 180 m.
Time taken = distance / speed.
⇒ 180 / 45
⇒ 4 hours.
∴ The time taken by the truck to reach the camp is 4 hours.
<u>To find how long the kids have to wait for their bags :</u>
The time taken by the truck to reach the camp - the time it took for the kids to arrive.
⇒ 4 hours - 3 hours
⇒ 1 hour.
∴ The kids have to wait for 1 hour to get their bags.