# Greenwich Mean Time

**Work Time**

# Greenwich Mean Time

Since 1884, people on Earth have used the time of the meridian at Greenwich, England—known as Greenwich Mean Time—as the basis for standard time around the globe. The time at different places varies from 12 hours ahead of Greenwich Mean Time to 12 hours behind it, as shown on the map. Greenwich is near London. Regions whose time zone is shown in two colors are halfway between the time zones represented by those colors. For example, New Delhi is 5$\frac{1}{2}$ hours ahead of Greenwich Mean Time.

- Examine and interpret the map. Write three statements about the time in three different cities.
On the number line, label each city you discussed in problem 1 next to the number that represents its time zone. Use positive numbers for time zones ahead of Greenwich Mean Time and negative numbers for time zones behind it.

Use the number line from problem 2 to find what time it is in London and Tokyo when it is 8:00 p.m. in Chicago.

Complete the table. Find the times in the other cities when it is 8:00 p.m. in Chicago. Then find the number of hours each city is ahead of or behind London.

HANDOUT: Greenwich Mean Time