SOLUTION: I cannot do story problems. I am having trouble with two of them. I just need to know how i reach the answer 1.A plane flies 500mls with the wind and 340 against the wind in the

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Question 351312: I cannot do story problems. I am having trouble with two of them. I just need to know how i reach the answer
1.A plane flies 500mls with the wind and 340 against the wind in the same length of time. If the speed of the wind is 20mph what is the speed of the plane in still air. (95,110,130,105)? I know its d=rt but cant figure it out.
2.A contractor mixes concrete from bags of premix for small jobs. How many bags with 11% cement should he mix with 10 bags of 12.5% cement to produce a mix containing 12% cement? I know I am solving for X, or how many bags of 11% cement I need but cannot figure it out. (15,5,7,20)
Answer by solver91311(24713) (Show Source):
You can put this solution on YOUR website!

Your difficulties with story problems may well be related to your fundamental inability to follow written instructions. When you go to the page to post your questions, the instructions clearly state: "One question per post"

Let represent the speed of the plane in still air. Then must be the ground speed when the plane is traveling with the wind and must be the ground speed when the plane is traveling against the wind. Let represent the flight time in either direction.

Since we know that , we can also say:

For the with the wind trip:

For the against the wind trip:

Since the time was the same for both directions, we can say:

Solve for .

John

My calculator said it, I believe it, that settles it