Problem Solving
1 answer:
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Answer:
Step-by-step explanation:
Let the time flown by the flying carpet be . Then, we have that
.
We multiply both sides of the equation by to get
.
We subtract from both sides to get
.
We divide both sides of the equation by .
We know that the speed of the flying carpet in still wind is the average of the rates of the speed of the flying carpet with the wind and against the wind.
The speed with wind is mph.
The speed against wind is mph.
The speed in still wind is .
Therefore, the answer is and we're done!
Answer: 15/91 which is choice B
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There are two methods to find this answer.
Method 1) We have 6 girls and 8+6 = 14 students. The probability of picking a girl is 6/14 = 3/7. After the first girl is chosen, we have 5 girls left out of 14-1 = 13 students overall. The probability of picking another girl (assuming the first selection was a girl) is 5/13. Multiply these probabilities: (3/7)*(5/13) = (3*5)/(7*13) = 15/91
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Method 2) We can use the nCr combination formula. Order does not matter.
We have nCr = 6 C 2 = 15 ways to pick 2 girls. See the attached image below for the steps (figure 1)
Out of nCr = 14 C 2 = 91 ways to pick 2 students. See the attached image below for the steps (figure 2)
So that's another way to get the answer 15/91.
