If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:3:46

Comparing linear functions word problem: work

Video transcript

Charles and Tammy lived the same distance from work and they started walking to work at the same time they both walked at constant speeds though not necessarily not necessarily at the same speed Charles's distance from work is shown in the following table so at 50 seconds he's 830 meters from work then another 50 seconds goes by now he's 70 760 meters from work another 50 seconds goes by and he's 690 meters from work which makes sense he's getting closer and closer to work as seconds passed by he's walking to work which of these sentences could possibly be true select all that apply so what are these sentences talking about so it looks like they're all talking about Tammy Tammy started 830 meters from work and walked towards work at two meters per second she started 900 meters per work from work and walked towards work at 750 meters per second so all of these seem to be statements about where did Tammy start and how quickly did she walk to work so let's think about which of these could possibly be true well the one thing that we know is that they live the same distance from work so the distance that Charles started walking from work that's the same distance that Tammy started walking from work so let's figure out what that distance is so we see that every 50 seconds so if we go from 50 to 100 seconds so if we have we add 50 seconds or 50 seconds go by it looks like Charles traveled another let's see this is to go from from 8:30 to 760 his distance from work decreased decreased by 70 by 70 meters and let's see if that keeps holding up it should because they're moving at constant speeds another 50 seconds goes by and his distance from work decreases by another 70 meters so what would have happened 50 seconds in the past so what would have happened at zero seconds so 50 seconds before he is at 830 meters he would have been 70 meters further from work so he would have been 9 900 meters for work we see this consistent when fifty seconds passed by when fifty seconds passed by when you go from zero seconds to fifty seconds he goes from nine hundred meters away to 70 meters away so once again his distance from work decreases by seventy then another 50 seconds goes by decreases by 70 again another 50 seconds decreases by 70 again so at time zero Charles was 900 meters away from work now we know that Tammy and Charles live the same distance away from work so Tammy would have also started 900 meters away from work now they tell us that they don't necessarily walk at the same speed so we don't know what Tammy's speed is this this hasn't in any way constrained Tammy speed so we know that she started 900 meters away so we know that this can't be the case in essence 8:30 we know that this can't be the case we know that this can't be the case because they all talk about starting in a distance other than 900 meters and over here both of these they say she started at 900 meters from work and walked towards work at 750 meters per second well that's possible it's not necessarily true they haven't given us information on her speed but given the information so far this is definitely a possibility likewise Tammy started 900 meters from work we know that is true and walked towards work at 5/7 meters per second well once again that's a possibility that hasn't been ruled out by the information in this the information right over here so these are both these two are both possibly true