We cannot calculate the confidence interval without the sample size. However, for the second question, the sample size needed would be 49.
The formula we use is

To find the z-score:
Convert 98% to a decimal: 0.98
Subtract from 1: 1-0.98 = 0.02
Divide by 2: 0.02/2 = 0.01
Subtract from 1: 1-0.01 = 0.99
Using a z-table (http://www.z-table.com) we see that this value is closest to a z-score of 2.33.
Using the z-score, our standard deviation (9) and our margin of error (3), we have:
B is your awnser! sorry if im wrong my calc shows its without a - symbol
Answer:
15 minutes
Step-by-step explanation:
First, the motorcycle goes at a speed of 40 km/hr.
The question asks for how long it would take to travel 10 km.
Well, there are 60 minutes in an hour, since we will be translating into minutes.
Also, 10 km is 1/4 of 40 km, so it would make sense that the time length would be 1/4 of an hour as well.
1/4 of 60 minutes is 15 minutes. So it takes 15 minutes for the motorcycle to travel 10 km.
Now, if all this wordy stuff is too much to comprehend, you can also solve using proportional relationships.

Now cross multiply:

Divide both sides by 40:

Again, this shows that it wouls take 15 minutes for the motorcycle to travel 10 km.
Answer: idk the answer but i can tell u that u are trying to find the value of the symbols and the numbers :)
Step-by-step explanation: