For problems such as this, it can be handy to remember that
.. 1/(1/a +1/b) = ab/(a +b)
The time required to do a job is the inverse of the rate at which the job is done. Rates are added when people work together (in math problems, not in real life).
(2:44)*(3:14)/(2:44 +3:14) = 1:28:52.3
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2:44 = 41/15 hours = 82/30 hours
3:14 = 97/30 hours
Using the formula above, we have a "working together" time of
.. (82/30)*(97/30)/(82/30 +97/30) = 82*97/(30*179) = 3977/2685 . . . hours
.. = 1 hour 28 156/179 minutes
.. = 1 hour 28 minutes 52 52/179 seconds
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Learn to use the fraction functions on your calculator. They can be very helpful.
Answer:

Step-by-step explanation:
Data provided in the question:
Number of cups of tea offered = 3
Number of cups marked = 9
Number of cups tasted by each = 4
Now,
The probability that a contestant does not taste all of the samples
= contestant tastes only 2 samples of tea
=
C₆⁴ = number of ways to choose 4 cups out of 6 cups of two samples
C₃² = number of ways to choose which 2 samples will be tasted
[ as 2 samples × 3 cups each = 6 cups ]
C₉⁴ = Number of ways to choose 4 cups out of 9
= 
Hence,
the correct answer is option (B) 5/14
Answer: Choice A) 8.742 * 10^7
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Work Shown:

Extra info:

which is a little over 87.4 million
Answer:
8/5
Step-by-step explanation: