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Siblings Jason, Kent, and Larry decided to plant some seeds in their garden. They started promptly starting at 1:00pm. With the three of them working together, it should take three hours.At 2:55pm, Kent received a phone call and had to go. Jason and Larry continued to plant seeds.At 3:40pm, Jason hurt his hand and couldn’t continue. Larry decided to finish the job himself on that day. Assume each sibling worked at the same efficiency. When will Larry finish? Please give the answer in the format XX:YY.

 Jan 11, 2021
 #1
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SInce they work at the same speed,

  with all three working it will take 180 mins

    at 2:55 (after 115 mins) there is 180 - 115  = 65 mins  left if all 3 continued to work   

       since there are only two now working  the job will now take 

         65 *3/2=97.5 minutes  to complete 

 

   after another 45 minutes Jason candies out leaving   (97.5 -45) = 52.5 mins left   if both were working

     but since ONLY Larry is let working, it will take twice as long to finish = 105 minutes to finish

 

3:40 + 105 mins =   3:40 +  1hr 45 min = 4:25 pm 

 Jan 11, 2021
 #3
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Be careful when adding times, guest!

Pangolin14  Jan 12, 2021
 #2
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Let 1/T be the part of the whole work that each sibling does. We also have that the total time will be 1/T, so We have that 3/T = 1/3, so T = 9 hrs.

 

As they only worked for 115 minutes, and they were supposed to work for 3 hrs, they only got 115/180 = 23/36 of the job done.

 

Two people working together will get the job done in 4.5 hrs. So, as 2 people working at the same speed worked for 45 minutes, we have that they got 45/270 = 1/6 more, or 6/36, which adds to 29/36.

 

Next, we have to find how many hours it takes one person to finish 7/36 of a field. The answer is 9 * 7/36, or 105 minutes, or 1 hr 45 minutes, so 3:40 + 1:45  = 5:25.

 

Correct me if I made any mistakes.

 Jan 12, 2021

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