Question #4ee1e

2 Answers
Jan 25, 2018

The answer is 30 miles per hour.

Explanation:

Use the conversion factor "60 minutes in an hour" to convert the original speed (20"mi")/(40"min")20mi40min to miles per hour:

(20"mi")/(40cancel("min")) * (60cancel("min"))/(1"hr")=>

(20"mi")/40*60/(1"hr")=>

(1200"mi")/(40"hr") =>

(30"mi")/(1"hr")

Hence, the answer is 30 mph.

Jan 25, 2018

30" mph"

Explanation:

"using the relationship"

color(red)(bar(ul(|color(white)(2/2)color(black)("distance (D)"="average speed (S)"xx"time (T)"color(white)(2/2)|)))

rArrD=ST

"from this we can obtain"

S=D/T" and "T=D/S

"here we require speed (S) so using "S=D/T

"note that time is in hours and"

40" minutes "=40/60" hour "=2/3" hour"

S=D/T=20/(2/3)=(3xx20)/2=30" miles per hour"