95% of red lights last between 2.5 and 3.5 minutes.
<u>Step-by-step explanation:</u>
In this case,
- The mean M is 3 and
- The standard deviation SD is given as 0.25
Assume the bell shaped graph of normal distribution,
The center of the graph is mean which is 3 minutes.
We move one space to the right side of mean ⇒ M + SD
⇒ 3+0.25 = 3.25 minutes.
Again we move one more space to the right of mean ⇒ M + 2SD
⇒ 3 + (0.25×2) = 3.5 minutes.
Similarly,
Move one space to the left side of mean ⇒ M - SD
⇒ 3-0.25 = 2.75 minutes.
Again we move one more space to the left of mean ⇒ M - 2SD
⇒ 3 - (0.25×2) =2.5 minutes.
The questions asks to approximately what percent of red lights last between 2.5 and 3.5 minutes.
Notice 2.5 and 3.5 fall within 2 standard deviations, and that 95% of the data is within 2 standard deviations. (Refer to bell-shaped graph)
Therefore, the percent of red lights that last between 2.5 and 3.5 minutes is 95%
3 to the negative second power is written like this:

.
When simplifying an expression with a negative exponent, you take a positive version of the exponent, in this case that would be 2, and apply that to the base.
After doing that, we have 9.
The next step is to put one over that number.
In this case, now after doing that the answer is

.
Hope this helps!
Answer:
Discrete. See explanation below
Step-by-step explanation:
We need to remember some previous concepts:
We have two types of numerical data: Discrete and Continuous
When we say Discrete data we are refering to data that is countable or can be expressed with integers in a domain.
In the other case when we talk about continuous data we are refering to data that is continuous in a specified domain, it can contain decimals or rational numbers in the Real numbers for example.
For this special case we know that they select a sample size of n=1020 and the sample proportion of people in the United States who wash their hands after riding public transportation was 0.44 or 44% in percentage.


But the number of subjects on this survey needs to be Discrete, since the possible values are 0,1,2,3,4,.....,n and never we have decimals or continuous data in order to express this.
Answer:
290
Step-by-step explanation: