A simple random sample pf 50 adults was surveyed, and it was found that the mean amount of time that they spend surfing the internet per day is 54.2 minutes, with a standard deviation of 14.0 minutes. What is the 99% confidence interval (z-score = 2.58) for the number of minutes that an adult spends surfing the internet per day?

Answer: a. 49.1 minutes to 59.3 minutes.

Explanation:
Given:
sample population=50;
mean=54.2 minutes;
standard deviation=14.0 minutes;
z-score=2.58.
Solution:
Margin of error=z*δ/√n;
2.58*(14/√50)=2.58*14/7.07=2.58*1.98=5.1084 or 5.11;
54.2+5.11=59.31 minutes;
54.2-5.11=49.09 minutes.
Hence, option a is correct.

Cost of 7 gallons=$24.50

Cost of 1 gallon=24.50/7=3.5

Cost of 15 gallons=15*3.5=52.5

Cost of 15 gallons will be $52.5

The answer is in the image 

The solution is in the following image

The answer is in the image 

F=ma

where F=force

m=mass

a=acceleration

Here,

F=4300

a=3.3m/s2

m=F/a

    =4300/3.3

    =1303.03kg

Approximately it is aqual to 1300kg

The answer is in the image 

The answer is in the image 

Speed=Distance/time

Here,

distance=15m

time=1sec

speed=15/1=15m/sec

Distance=Speed*time

time=15min=15*60sec=900sec

Distance travelled in 15 min=15*900=13,500m

=13500/1000 km=13.5Km