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Question 1184425: Is it 90 minutes? I want to check my answer.
Ali has hired Mark and Alexis to work for his shipping company. Mark can load a truck with packages in 120 minutes. Alexis can load the same number of packages in 240 minutes.
If Mark and Alexis work together on a particular truck, they can load all of the packages in 90 minutes.
Found 4 solutions by ikleyn, MathLover1, MathTherapy, greenestamps:
Answer by ikleyn(52772)   (Show Source):
You can put this solution on YOUR website! .
Ali has hired Mark and Alexis to work for his shipping company.
Mark can load a truck with packages in 120 minutes.
Alexis can load the same number of packages in 240 minutes.
If Mark and Alexis work together on a particular truck, they can load all of the packages in 90 minutes.
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As you posed, worded and presented the problem in your post, it is I N C O R R E C T.
This incorrect formulation confuses YOU and other readers.
THEREFORE, I reformulate the problem AS IT SHOULD BE.
Ali has hired Mark and Alexis to work for his shipping company.
Mark can load a truck with packages in 120 minutes.
Alexis can load the same number of packages in 240 minutes.
If Mark and Alexis work together, how long will it take to load a truck ?
For this COPRRECTLY POSED PROBLEM, see my solution below.
Mark makes  of the job per hour. It is his rate of work.
Alexis makes  part of the job per hour. It is his rate of work.
Working together, they make  =  =  of the job per hour.
It means that they will complete the entire job in  hours, working together.
hours is 1 hour and 20 minutes.
ANSWER. They will complete the job in 1 hour and 20 minutes.
Solved.
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.
It is a standard and typical joint work problem.
There is a wide variety of similar solved joint-work problems with detailed explanations in this site. See the lessons
- Using Fractions to solve word problems on joint work
- Solving more complicated word problems on joint work
- Selected joint-work word problems from the archive
Read them and get be trained in solving joint-work problems.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this textbook under the topic
"Rate of work and joint work problems" of the section "Word problems".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.
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Answer by MathLover1(20849)  (Show Source):
Answer by MathTherapy(10551)  (Show Source):
You can put this solution on YOUR website! Is it 90 minutes? I want to check my answer.
Ali has hired Mark and Alexis to work for his shipping company. Mark can load a truck with packages in 120 minutes. Alexis can load the same number of packages in 240 minutes.
If Mark and Alexis work together on a particular truck, they can load all of the packages in 90 minutes.
NOPE...You and the other person are WRONG.
She's wrong most times, anyway. So, pay NO ATTENTION to her answer.
Correct answer: 
Answer by greenestamps(13198)  (Show Source):
You can put this solution on YOUR website!
Here are a couple of other ways to solve this and other similar problems.
(1) Alexis takes twice as long to do the job as Mark, so she does half as much work in the same amount of time. So when working together the two of them are like 3/2 workers. That means together it will take them 2/3 as long to do the job.
2/3 of 120 minutes is 80 minutes.
(2) Consider the least common multiple of the two given times, which is 240 minutes. In 240 minutes Mark could do the job 2 times and Alexis could do it once; so together in 240 minutes they could do the job 3 times. And that means they could do the job together 1 time in 240/3=80 minutes.
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