I'm guessing 90 hours because if you add their hours together it'll be 180 if they work together it'll be like half the time which is 90
Answer:
Option (D)
Step-by-step explanation:
Subtraction property of equality tells that whatever subtracted from one side of the equation must be subtracted from the other side.
If x + 2 = 2,
By the property of subtraction of equality,
x + 2 - 2 = 2 - 2
x = 0
But in the given question,


shows the addition property of equality in step (2)
Therefore, subtraction property of equality was not applied.
Option (D) will be the answer.
The problem statement gives you the relationship between their speeds, and it gives you information you can use to find their total speed. You solve this by finding the total speed, then the proportion of that belonging to Bill.
The total speed is (120 mi)/(3 h) = 40 mi/h.
The speed ratio is ...
... Bill : Joe = 3 : 1
so the speed ratio Bill : Total is ...
... 3 : (3+1) = 3:4.
Bill's speed is (3/4)×(40 mi/h) = 30 mi/h.
Answer:
C. 50
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.

In which
z is the zscore that has a pvalue of
.
The margin of error is:

The higher the margin of error, the wider an interval is.
As the sample size increases, the margin of error decreases. If we want a widest possible interval, we should select the smallest possible confidence interval.
So the correct answer is:
C. 50