General Mathematics HSC Time Zones Stage 6 Year

General Mathematics HSC Time Zones Stage 6 - Year 12 Press Ctrl-A ©G Dear 2009 – Not to be sold/Free to use 1

Time Zone (1/9) Time zones are calculated in relation to GMT. Greenwich Mean Time For locations to our east we add time. Sydney = Adelaide + 30 min = 9 am + 30 min = 9: 30 am Map Adelaide 9 am Sydney 9: 30 am 2

Time Zone (1/9) Time zones are calculated in relation to GMT. Greenwich Mean Time For locations to our east we add time. For locations to our west we subtract time. Perth = Adelaide – 1 hr 30 min = 9 am - 1 hr 30 min = 7: 30 am Perth 7: 30 am Map Adelaide 9 am 3

Time Zone (2/9) If it is 7: 08 am [07: 08 hrs] hours in London … … what time is it in Sydney? Map Sydney = London + 10 hr [East] = 07: 08 + 10 hr = 17: 08 = 5: 08 pm 4

Time Zone (3/9) If it is 10: 20 am [10: 20 hrs] hours in Sydney … … what time is it in Honolulu? Honolulu = Sydney - 20 hr [West] = 10: 20 - 20 hr = -10: 20 + 24: 00 = 14: 20 yesterday = 2: 20 pm yesterday Map 5

Time Zone (4/9) If it is 10: 20 am [10: 20 hrs] hours in Sydney … … what time is it in Honolulu? Honolulu = Sydney + hr [East] = 10: 20 + 4 hr [Crossing ‘Date Line’ subtract one day] = 14: 20 = 2: 20 pm yesterday Map 6

Time Zone (5/9) When crossing the International Date Line… • going east – subtract one day • going west – add one day When determining time zones 1 o in longitude equals 4 minutes. o 15 in longitude equals 1 hour. Map 7

USA Time Zones (6/9) 75 o. W Time Zone = -75 x 4 mins = -300 mins = -5 hrs Map 8

USA Time Zones (7/9) 90 o. W 75 o. W -5 Time Zone = -90 x 4 mins = -360 mins = -6 hrs Map 9

USA Time Zones (8/9) 105 o. W 90 o. W -6 75 o. W -5 Time Zone = -105 x 4 min = -420 mins = -7 hrs Map 10

USA Time Zones (9/9) 120 o. W -8 105 o. W -7 90 o. W -6 75 o. W -5 Time Zone = -120 x 4 min = -480 mins = -8 hrs Map 11