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Difficulty: MediumTime Measurements and Calculations

A maintenance crew is scheduled to overhaul a radar system. The procedure consists of three sequential phases: diagnostics taking 11 hour and 4545 minutes, component replacement taking 22 hours and 3030 minutes, and recalibration taking 5555 minutes. If the crew begins the overhaul at 09200920 hours, at what time will the entire procedure be completed?

  1. A
    12301230 hours
  2. B
    13501350 hours
  3. 14301430 hoursAnswer
  4. D
    14361436 hours

Answer

The entire procedure will be completed at 14301430 hours.
The total duration of the three phases is 310 minutes, which converts to exactly 5 hours and 10 minutes. When you add this elapsed time to the starting clock time of 0920 hours, the final completion time correctly evaluates to 1430 hours.

Step-by-Step Solution

1
Convert the duration of all three phases into minutes to standardize the units.
Phase 1: 1 hour 45 minutes = 105 minutes. Phase 2: 2 hours 30 minutes = 150 minutes. Phase 3: 55 minutes.
Converting all times to a single unit prevents base-60 addition errors across mixed units.
2
Calculate the total duration of the overhaul by summing the minutes.
105 + 150 + 55 = 310 minutes.
The total time required is the sum of all individual phases.
3
Convert the total duration back into hours and minutes.
310 minutes divided by 60 equals 5 hours with a remainder of 10 minutes (5 hours and 10 minutes).
You must express the total elapsed time in hours and minutes to add it directly to a clock time.
4
Add the total duration to the starting time of 0920 hours.
0920 + 5 hours = 1420 hours; 1420 hours + 10 minutes = 1430 hours.
Adding the elapsed time to the initial clock time determines the final completion time.

Key Concept

Calculating total elapsed time by converting between minutes and hours (using a base-60 system) and applying it to a 24-hour military clock.

Alternative Method

Instead of converting to minutes, you can group the hours and minutes separately: Add the whole hours (1 hour + 2 hours = 3 hours). Then add the minutes (45 + 30 + 55 = 130 minutes). Convert the 130 minutes to 2 hours and 10 minutes, and combine this with the 3 hours to get a total duration of 5 hours and 10 minutes.
Estimated Time:1m 30s
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Topics

Time Measurements and Calculations

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