a car covers a distance of 490 km with a speed of 70km and then covers a speed of 90km calculate its average speed
1 answer:
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M = hours driven by Maria
c = hours driven by Carlos
since we know that Carlos was driving at an average of 52 mph, then in 1 hour he drove 52 miles, in 2 hours he drove 2*52 miles in "c" hours he drove c*52 miles or 52c.
Maria on the other hand is faster and does 54 mph, in 1 hour she does 1 * 54 miles, and on 2 hours she does 2 * 54 miles and in "m" hours she does m * 54 miles or 54m.
now, we know the total amount of miles they both drove is 217, so whatever "m" and "c" are we know that 54m + 52c = 217.
we also know it took 4.1 for the whole trip, so m + c = 4.1.
so Maria drove for 1.9 hours.
How many hours did Carlos drive for? well, c = 4.1 - m.
c = hours driven by Carlos
since we know that Carlos was driving at an average of 52 mph, then in 1 hour he drove 52 miles, in 2 hours he drove 2*52 miles in "c" hours he drove c*52 miles or 52c.
Maria on the other hand is faster and does 54 mph, in 1 hour she does 1 * 54 miles, and on 2 hours she does 2 * 54 miles and in "m" hours she does m * 54 miles or 54m.
now, we know the total amount of miles they both drove is 217, so whatever "m" and "c" are we know that 54m + 52c = 217.
we also know it took 4.1 for the whole trip, so m + c = 4.1.
so Maria drove for 1.9 hours.
How many hours did Carlos drive for? well, c = 4.1 - m.