A.LET X EQUAL THE AMOUNT OF TIME PASSED. SINCE THE TIME REMAINING...

70. a.Let x equal the amount of time passed. Since the time remaining is of the time that has passed,

4

1

this time can be represented as .Converting to decimal form may make this problem easier, so

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xchange to .25x. Since 1xis the time passed and .25xis the time remaining, then 1x+ .25xis thetotal time. This is equal to 1.25x. To calculate the percent of the period that is over, use the proportion

part

whole

100

^%

Now set up a proportion using the time passed as the part and the total time for the class as the whole.