Question 1206989
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Answer: <font color=red>2/5</font>


Explanation


The "1 l" looks a lot like two lowercase L's put together.
Perhaps your teacher should have written it as "1 L" or "one liter".


x = number of seconds that elapse
y = amount of water, in mL, in the tank


The equation is
y = -5x+1000


This is because the equation is of y = mx+b form
m  = -5 = slope = how much water in mL leaks per second
b = 1000 = starting number of mL of water
1000 mL = 1 liter


If we plugged x = 0 into y = -5x+1000, then we'd get y = 1000.


Plug x = 120 into the equation to find that y = -5*(120)+1000 = 400


At the 2 minute marker, aka 120 seconds, 400 mL of water remains.
400/1000 = <font color=red>2/5</font> of the tank is full by this point.


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Another approach


1 liter = 1000 mL
1 mL = 1/1000 = 0.001 liter
1 mL = 0.001 liter
5*1 mL = 5*0.001 liter
5 mL = 0.005 liter


The tank is losing 0.005 liters of water per second.
After 120 seconds (aka 2 minutes), the tank lost 120*0.005 = 0.6 liters of water.
The amount remaining is 1 liter - 0.6 liters = 0.4 liters
Divide this over the tank's capacity of 1 liter to get 0.4, note the "liters" units cancel when dividing.


Then convert that to a fraction
0.4 = 4/10 = <font color=red>2/5</font>
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