GARA DI BACHECA 2015 2016: QUESITO N°9

DRIVE IN THE CAR

PT.10

Jon drives from his home to the store at an average speed of  40 kilometers per hour. He drives back home from the store at an average speed of 60 kilometers per hour. Assume the distance he travels in these two trips is the same. His average speed for the entire trip is how many kilometers per hour?

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RISPOSTA QUESITO N°8: 144

scade il  26 gennaio

HANNO RISPOSTO CORRETTAMENTE: (10PT)

RISOLUZIONE:  This is an arithmetic progression with initial term 1, common difference 2, and number of terms 12. Hence, the sum of all terms is [1+(1+11x2)]x12 /2=144