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Sia

Question
Math
Posted 11 months ago
this can draw image omg!
It takes Kate k days to write a GRE math practice test. It takes John j days to write a GRE math practice test. If Kate and John work on a practice test in alternating 2-day shifts, it takes them 10 days when Kate starts and 10.5 days when John starts. How long would it take the two to complete a practice test if Kate and John worked simultaneously?
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Answer from Sia
Posted 11 months ago
Solution by Steps
step 1
To find the values of k k and j j , we solve the system of equations given by the alternating shifts
step 2
The system of equations is k2+10k2=10\frac{k}{2} + \frac{10 - k}{2} = 10 and j2+10.5j2=10.5\frac{j}{2} + \frac{10.5 - j}{2} = 10.5
step 3
Solving the system, we find that k=10 k = 10 and j=10.5 j = 10.5
step 4
To find the time taken if Kate and John work simultaneously, we use the formula 1k+1j\frac{1}{k} + \frac{1}{j}
step 5
Substituting k=10 k = 10 and j=10.5 j = 10.5 into the formula, we get 110+110.5\frac{1}{10} + \frac{1}{10.5}
step 6
Simplifying, we find the combined work rate to be 110+221=21210+20210=41210\frac{1}{10} + \frac{2}{21} = \frac{21}{210} + \frac{20}{210} = \frac{41}{210}
step 7
The time taken for both to complete the test working simultaneously is the reciprocal of the combined work rate, which is 21041\frac{210}{41}
Answer
21041 \frac{210}{41} days or approximately 5.12 days
Key Concept
Combined work rate when working simultaneously
Explanation
When two people work simultaneously, their work rates add up. To find the total time taken, we take the reciprocal of the combined work rate.

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