Answer:
D
Step-by-step explanation:
irdk sorry if its wrong :(
Check photo for answer! i have included work
Answer:
a)
And we can find this probability using the normal standard table or excel and we got:
b)
And we can find this probability using the complement rule and the normal standard table or excel and we got:
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Part a
Let X the random variable that represent the time for the step 1 and Y the time for the step 2, we define the random variable R= X+Y for the total time and the distribution for R assuming independence between X and Y is:
Where
and
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:
And we can find this probability using the normal standard table or excel and we got:
Part b
And we can find this probability using the complement rule and the normal standard table or excel and we got:
SOLUTION
Given the question in the image, the following are the solution steps to answer the question.
STEP 1: State the number of outcomes possible for three tossing of a coin
Since a coin has two possible outcomes and is tossed three times, the total outcomes will be:

STEP 2: Find the number of sample spaces for the three tosses
STEP 3: Get the outcomes of the events for which the second toss is tails
Hence, the answers are given as:
Sample Space:

The event that the second toss is tails: