City X is located at longitude 15^\circ\text{E}. When the local time at City X is 2:00\tex… — JAMB UTME

City X is located at longitude $15^\circ\text{E}$ . When the local time at City X is $2:00\text{ PM}$ , what is the local time at City Y, located at longitude $45^\circ\text{E}$ ?

$4:00\text{ PM}$ Answer
B
$12:00\text{ noon}$
C
$3:00\text{ PM}$
D
$1:00\text{ PM}$

Answer

The local time at City Y is

4:00\text{ PM}

The difference in longitude between City X (

15^\circ\text{E}

) and City Y (

45^\circ\text{E}

) is

30^\circ

. Since

15^\circ

corresponds to 1 hour,

30^\circ

equals 2 hours. Because City Y lies to the east of City X, local time is ahead, so 2 hours must be added to

2:00\text{ PM}

, giving

4:00\text{ PM}

Step-by-Step Solution

Calculate the angular longitudinal difference between City X and City Y.

Difference

= 45^\circ\text{E} - 15^\circ\text{E} = 30^\circ

Since both cities are in the Eastern Hemisphere, subtract the smaller longitude from the larger longitude.

Convert the longitudinal difference into a time difference.

Time difference

= 30^\circ \div 15^\circ/\text{hour} = 2\text{ hours}

The Earth rotates

15^\circ

per hour (

360^\circ

in 24 hours).

Determine whether to add or subtract the time difference.

Local time

= 2:00\text{ PM} + 2\text{ hours} = 4:00\text{ PM}

City Y (

45^\circ\text{E}

) is east of City X (

15^\circ\text{E}

), so time is ahead (gain time going east).

Key Concept

Calculation of local time difference using longitudinal intervals

Estimated Time:45s

Question

Answer

Step-by-Step Solution

Key Concept

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