Based on an online poll, 35% of motorists routinely use their cell phone while driving. Tree people are chosen at random from a
1 answer:
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Answer:
a: Sample mean: 20, Sample standard deviation: 1.732
b: 19.13 <µ < 20.87
c: 18.84< µ < 21.16
d: as the confidence level increases, the interval becomes wider
Step-by-step explanation:
a: Sample mean is found by adding up all the individual values of the sample, then dividing by the total number of values in the sample.
Sample standard deviation is the square root of the variance
See the first attached photo for the calculations of these values.
We need to create a 80% confidence interval for the population. Since n < 30, we will use a t-value with degree of freedom of 7 (the degree of freedom is always one less than the sample size.
Look for the column on the t-distribution chart that has "area in two tails" of 0.20 (80%), and row 7 (degree of freedom)
The t-value is 1.415
See the second attached photo for the construction of the confidence interval
We need to create a 90% confidence interval for the population. Since n < 30, we will use a t-value with degree of freedom of 7 (the degree of freedom is always one less than the sample size.
Look for the column on the t-distribution chart that has "area in two tails" of 0.10 (90%), and row 7 (degree of freedom)
The t-value is 1.895
See the third attached photo for the construction of the confidence interval
Answer:
Probability that Adam and Ella will be selected:
Step-by-step explanation:
Probabilities
The probability of a random event E to occur is a real number between 0 and 1, both inclusive, where 0 indicates an impossible event and 1 a sure event. There are many techniques to compute probabilities depending on the particular situation and distribution.
This question will be solved by simple calculations and logic, given its simplicity. We know the middle school chess club has 5 members: Adam, Bradley, Carol, Dave, and Ella. Two of them are going to be selected at random to participate in the county chess tournament. We can calculate the number of different ways it can be done without any restriction. It's called the sample space.
The sample space of this event is the combination of 5 members regardless of their position. If {a,b,c,d,e} are the five members, then the possible combinations are {ab,ac,ad,ae,bc,bd,be,cd,ce,de}. Notice that there are only 10 possibilities because the combination ab is the same as ba since it's the same team for the tournament.
We can see there is only one combination of two specific letters out of 10. If a=Adam and e=Ella, only one combination is ae, the other 9 don't include both members, so the probability is