A Coast Guard maritime patrol aircraft is assigned a 720-mile patrol route. To meet missio… — Armed Services Vocational Aptitude Battery (ASVAB)

A Coast Guard maritime patrol aircraft is assigned a $720$ -mile patrol route. To meet mission parameters, the aircraft must maintain an overall average speed of $180$ miles per hour from start to finish. The crew completes the first $480$ miles at a cruising speed of $320$ miles per hour, then lands at a coastal airfield for a $30$ -minute refueling stop. What average speed must the aircraft maintain during the final leg of the patrol to achieve the required overall average speed?

A
40 mph
B
80 mph
C
100 mph
120 mphCevap

Cevap

The aircraft must maintain an average speed of

120

mph for the final leg.

The correct answer is found by first determining the total mission time (

720 \div 180 = 4

hours). Next, find the time used for the first leg (

480 \div 320 = 1.5

hours) and add the

30

-minute (

0.5

hour) stop, meaning exactly

2.0

hours have elapsed. Subtracting this from the total time gives

2.0

hours remaining to cover the final

240

miles. Dividing

240

miles by

2.0

hours yields exactly

120

mph.

Adım Adım Çözüm

Calculate the total time allowed for the entire mission.

720 \text{ miles} \div 180 \text{ mph} = 4 \text{ hours}

Overall average speed equals total distance divided by total time.

Calculate the time spent flying the first leg.

480 \text{ miles} \div 320 \text{ mph} = 1.5 \text{ hours}

(or

1

hour and

30

minutes)

Time equals distance divided by speed.

Calculate the total time used so far, including the refueling stop.

1.5 \text{ hours} + 0.5 \text{ hours} = 2.0 \text{ hours}

The

30

-minute refueling stop must be added to the flight time to find the total elapsed time.

Determine the remaining time available for the final leg.

4.0 \text{ hours} - 2.0 \text{ hours} = 2.0 \text{ hours}

Subtracting the elapsed time from the total allowed time gives the time limit for the remainder of the trip.

Determine the remaining distance to travel.

720 \text{ miles} - 480 \text{ miles} = 240 \text{ miles}

Subtracting the distance already covered from the total distance gives the remaining distance.

Calculate the required average speed for the final leg.

240 \text{ miles} \div 2.0 \text{ hours} = 120 \text{ mph}

Speed equals distance divided by time.

Anahtar Kavram

To find a required average speed for a remaining segment, subtract the distance already traveled from the total distance, subtract the time already spent (including stops) from the total allowed time, and divide the remaining distance by the remaining time.

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