Question

Bob travels in an airplane a distance of 1560 miles. For one-fourth of the distance, the airplane flies at a speed of 680 miles per hour,and for the rest of the distance, it flies at a speed of 780 miles per hour. How long the trip take?

Answer 1

Answer:

Bob's trip took 2.074 hours long.

Step-by-step explanation:

The journey is divided into two parts.

We can call these part A and B.

We break this down as follows :

Part A:

Distance = ¼ of the total distance.

This is calculated as follows :

¼ × 1560 = 390

Speed = 680 miles per hour

Now, Time = Distance / Speed

Time for part A is therefore :

390/680 = 39/68 hours

Part B:

Distance = 1560 - 390 = 1170

Speed = 780 miles per hour

Time = 1170/780 = 1½ hours.

The total time taken is given by:

= Time taken in part A + Time taken in part B

We do the substitution below:

1½ + 39/68 = 2.074 hours

So the journey took 2.074 hours.

Answer 2

Answer:

Bob's trip took 2.074 hours long.

Step-by-step explanation:

The journey is divided into two parts.

We can call these part A and B.

We break this down as follows :

Part A:

Distance = ¼ of the total distance.

This is calculated as follows :

¼ × 1560 = 390

Speed = 680 miles per hour

Now, Time = Distance / Speed

Time for part A is therefore :

390/680 = 39/68 hours

Part B:

Distance = 1560 - 390 = 1170

Speed = 780 miles per hour

Time = 1170/780 = 1½ hours.

The total time taken is given by:

= Time taken in part A + Time taken in part B

We do the substitution below:

1½ + 39/68 = 2.074 hours

So the journey took 2.074 hours.