IMAT 2017 Q3 [Time Zones]

Sheelagh runs a business from London with regional headquarters located in seven cities –Jakarta, Nairobi, Prague, Ottawa, Moscow, Canberra and Hong Kong. The company also has plants in other cities shown in the table. Her senior managers at regional headquarters work from 8 am to 5.15 pm local time and constantly check their emails between these hours but are not available outside these hours. All her staff have an international time chart displayed at their place of work.

At 12 noon in London it is:


At 3 pm in London she sends an urgent email to all her senior managers at her regional headquarters.

What is the longest possible interval between the first and last of her senior managers reading the email?

A. 9 hours
B. 14 hours
C. 17 hours
D. 16 hours
E. 7 hours

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Simple steps to solve word problems:

  • Underline key information
  • Determine what they are trying to ask, and what you will need to solve it
  • Eliminate any non-essential information
  • Draw a picture, graph, or equation
  • In moments of high stress like exam taking, always work with the paper they give you to avoid careless mistakes.
  • Solve.

This question is trying to give you a sensory overload. First, let’s slow down and ignore the table, to begin with. We are given the window that the emails may be received, and we are given the time it was sent in London time.

Approach: Find a place that has just closed when the email is sent, so you are forced to wake from practically closing time till opening time (which is the largest time window possible). What do I mean by “just closed”? Well if the last email could be received by 5:15 pm, then it must be a place where the time is as close as possible to $5:15$pm but still being closed. If we now take a look at the table, you will see that we are only working with whole hours, so 6 pm will be the earliest closed place that cannot receive emails (because you sent the email at 3 pm UK time, and we are only working with whole hours).

Now that we know all of this, we can take 6pm - 3pm = 3 hour difference

So we need to find a place that is 3 hours ahead. This would be Moscow from our list because it is 3 pm in Moscow while it is 12 pm in London. This is an important step because there is a chance that there are no places exactly 3 hours ahead, maybe there are only places 4 hours ahead. 3 hours is the best case (meaning the longest time possible) but there may be another option that is just the best of the options provided.

So, our final step is taking the number of hours between 6 pm and the 8 am opening time.

The difference between 6 pm and 8 am is 14 hours.

\fcolorbox{red}{grey!30}{Therefore the answer is B, $14$ hours. }