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$30\%$ finish their job in $122\mathrm s$, $30\%$ finish their job in $68\mathrm s$, and $40\%$ finish their job in $190\mathrm s$. What is the average time it takes for a person to finish their job?

This is what I thought: $$\frac{122\times\frac3{10}x + 68\times\frac3{10}x + 190\times\frac4{10}x }x = 133$$

But I feel like it was a long time ago I did something like this so I don't know if it is correct.

Chetan Vuppulury
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Agent smith 2.0
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    This is the correct approach to the problem! – atul ganju May 29 '20 at 09:29
  • Lol, this has nothing to do with division algebras! – J. De Ro May 29 '20 at 09:35
  • of course you can skip the x (=number of jobs) in such calculations because it cancels out. The average value is value_1q_1+value_2q_2+..., where q_i is the fraction of items thtat have value value_i, that is percentage_i/100. – miracle173 May 29 '20 at 10:36

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