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Family Physician
Family Physician, Internet Researcher
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Experience:  Researching answers to questions online for 20+ years.
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Math Question

Customer Question

A traffic light is red for 30 seconds, yellow for 5 seconds, and green for 40 seconds. What is the probability that when you reach the light, the light is red, the light is yellow, the light is not red.

a. 0.4, 0.6, 0.07
b. 0.6, 0.93, 0.4
c. 1.4, 1.07, 1.6
d. 0.4, 0.07, 0.6
e. 1.6, 1.93, 1.4

 

Use a product table to determine the number of 3-digit numbers that can be written using digits from the set {1, 2, 3, 4}. (Hint: In this case the product table would have to be three-dimensional.)

a.64 possibilities b.none of these are correct c.32 possibilities d.27 possibilities e.9 possibilities

Submitted: 9 years ago.
Category: General
Expert:  Family Physician replied 9 years ago.
For the first question:

Red = 30 seconds
Yellow = 5 seconds
Green = 40 seconds

Total cycle time: 75 second
Red 30/75 = 0.4
Yellow 5/75 = 0.0666...
Green 40/75 = 0.533...

When rounded you get 0.4, 0.07 and 0.5 (This is NOT one of the answers...the closest of course is D)

The second question has a link to a graphic - I could not get the link to work. If you can upload the graphic again - we can proceed with the last question.

Customer: replied 9 years ago.
Reply to FamilyPhysician's Post:

Use a product table to determine the number of 3-digit numbers that can be written using digits from the set {1, 2, 3, 4}. (Hint: In this case the product table would have to be three-dimensional.)

a. 64 possibilities
b. none of these are correct
c. 32 possibilities
d. 27 possibilities
e. 9 possibilities

Expert:  Family Physician replied 9 years ago.
GREAT...Thanks
You have 64 possibilities (assuming that you are allowed to use a digit more than once in each number such as 111 or 121:
This is calculated by multiplying the number of possible choices at each location (1st, 2nd and 3 digit) 4*4*4 = 4^3 = 64

Here are all the possibilities: Link
Family Physician and 47 other General Specialists are ready to help you
Expert:  Family Physician replied 9 years ago.
By the way: If yo were NOT able to reuse a digit you would have fewer possible numbers:

You would have 4 choices for the first digit, 3 choices for the 2nd digit, and only 2 choices for the 3rd digit.

4*3*2 = 24 different numbers

ALSO: Another expert PM me to point out that I had misread the first question: The question for the last part was the probability that it was NOT red (that would indeed make D the CORRECT ANSWER since it would be 0.5333... plus 0.0666...)
Customer: replied 9 years ago.
Reply to FamilyPhysician's Post: Thanks again.....