Question

A car travels 3/2 hours with a speed of 65kmph and then travels for 45minutes with a constant speed of 80kmph . Find the average speed.​

Answer 1

Answer:

70 kmph

Explanation:

avg speed = total dist / total time

total dist = (3/2 * 65) + (45/60 * 80)

               =  97.5 + 60

               = 157.5 km

total time = 3/2 + 45/60

                =9/4

avg speed = 157.5/9/4 = 157.5 * 4/9 = 70 kmph

Answer 2

Answer:

the formula for average speed is total distance devided by total time or

avg. speed= total distance / total time

when it's said 3/2 hrs it means 3/2 part of 1 hour which is 1.5 hrs

now first calculate the distance which it travelled for 1.5 hrs which will be distance = speed × time

hence distance = 1.5×65 = 97.5 km

now let's calculate the distance for second part as there is a change in speed so. distance = speed × time

hence distance = 80 × 0.75

= 60 km

Explanation:

now u must be thinking why i took 0.75, it's because 45 minutes is the 0.75 part of 1 hour.

now we have both distances and both times

now as i told u earlier. (avg. speed= total distance/ total time)

apply this

so your avg. speed will be

= 97.5+60/ 0.75+1.5

= 157.5/2.25

= 70