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# Rational number word problem: stock

Use your knowledge of proportions and fractions to determine shareholders profit in this word problem. Created by Sal Khan.

## Want to join the conversation?

• how come sal divided 4,200 by 4,200 and 4,050 and 2,510?
• Sal did that because you have to divide Mary's shares by the total amount of shares. If you have 4 slices of pizza, you ate 1 of the 1+1+1+1 pieces. If you did not include the slice of pizza you ate (Mary's shares), you would've gotten 1/3. That is why you need to include Mary's shares in the denominator along with the other two.
• Why did Sal divide 4200/(4050+250+4200) to get the answer?
I just don't get it because dividing Mary's shears by everyone get the answer.
• Haha ... Mary's shears? Didn't know she was a gardener now. :D
Ok, now to answer your question. Sal wanted to simplify the fraction and the only way to do that was to divide. As you know a fraction is basically a stood-up division problem so that's why he divided. Once he simplified it, it was a decimal . The decimal is how much of the shares she owns.
• why does the calculator look so real?
• why's he using a calculator, he should get a piece of paper or something and do it himself
• he pretty much just did it in front of us. Sal uses the drawing app he uses to show us how to solve the problem, and then he sometimes uses a calculator to check his own work to make sure HE didn't make a mistake and wouldnt have to re-record the video. we are all human, so it is very important to check our work for possible mistakes, but it is also important to know how to solve things on paper. :)
(1 vote)
• why not just add the three numbers at the bottom
(1 vote)
• I tried to solve this but got a different answer that is similar to Sal's but can anyone explain to me how he got that answer? the answer im looking at is at of the video.
(1 vote)
• When I divide 4,050 + 2,510 + 4,200 Which is 10,760. Divided by 4,200 ( 2.5619047 ) how do I get what Khan's got
• 4.200/10.760 = 0.39... What you did was 10.760/4.200 which does give 2.5. Basically you switched the numbers.