Question

To convert between miles and kilometers, the following formula is used:

8M= 5k where M is the number of miles and k is the number of kilometers.
If the speed limit is 100 kilometers per hour, what is the speed limit in miles per
hour?

Answer 1

Explanation:

you must have misunderstood. a mile is much longer than a kilometer.

so, the relation is correctly (but still only roughly)

8 kilometers = 5 miles

100 km = 8×x km

x = 100/8 = 25/2 = 12.5

now, we need to apply the same factor to 5 miles

5×12.5 miles = 62.5 miles per hour

so, 100 km/h = 62.5 miles/h

now, if the relation would truly be

8 miles = 5 kilometers

then

100 km = 5×x km

x = 100/5 = 20

now we apply the same factor to the miles and get

8×20 miles = 160 miles

and 100 km/h = 160 miles/h

but it is not.

these would be the correct numbers, if we asked what a speed limit of 100 miles per hour would be in kilometers per hour.

and yes,

100 miles/h = 160 km/h