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Frank ran 65 km on Monday, 68 km on Tuesday, 66 km on Wednesday, and 80 km on Thursday. After doing another run on Friday he calculated his mean distance run per day to be 70 km. How far did Frank run on Friday?

 Jan 10, 2020
 #1
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it is 71

 Jan 10, 2020
 #2
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[  65 + 68 + 66  + 80  +  R  ]  /  5 =    70       where R  = Friday's run

 

[ 279  + R ]  / 5  =  70              multiply both sides by 5

 

279 + R  =  350         subtract  279 from both sides

 

71 km  = R

 

 

cool cool cool

 Jan 10, 2020

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