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25 Dec 2025, 09:00
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Distance: 12
Intensity: 2
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
65% (01:56) correct
35%
(02:15)
wrong
based on 385
sessions
History
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Not Attempted Yet
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A point light source shines equally in all directions. The light intensity measured at a sensor is inversely proportional to the square of the distance from the source.
When the distance is 6 meters, the intensity is 8 units.
Select for Distance a distance in meters and select for Intensity an intensity in units that would be jointly consistent with the given information, Make only two selections, one in each column.
I31-38
| Distance | Intensity | |
| 2 | ||
| 4 | ||
| 12 | ||
| 16 | ||
| 24 | ||
| 32 |
ShowHide Answer
Official Answer
Distance: 12
Intensity: 2
25 Dec 2025, 10:00
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A point light source shines equally in all directions. The light intensity measured at a sensor is inversely proportional to the square of the distance from the source.
When the distance is 6 meters, the intensity is 8 units.
Select for Distance a distance in meters and select for Intensity an intensity in units that would be jointly consistent with the given information, Make only two selections, one in each column.
We are given that the intensity is inversely proportional to the square of distance, so Intensity = k/Distance^2, where k is a constant.
Since when D = 6 meters, I = 8 units, we have 8 = k/6^2, which gives k = 288.
Now check the options to find a pair (D, I) such that I = 288/D^2. Only (12, 2) fits. Thus, Distance = 12 meters and Intensity = 2 units.
GMAT-Club-Forum-e33ipien.png [ 12.12 KiB | Viewed 1922 times ]
When the distance is 6 meters, the intensity is 8 units.
Select for Distance a distance in meters and select for Intensity an intensity in units that would be jointly consistent with the given information, Make only two selections, one in each column.
GMAT Club Official Explanation:
We are given that the intensity is inversely proportional to the square of distance, so Intensity = k/Distance^2, where k is a constant.
Since when D = 6 meters, I = 8 units, we have 8 = k/6^2, which gives k = 288.
Now check the options to find a pair (D, I) such that I = 288/D^2. Only (12, 2) fits. Thus, Distance = 12 meters and Intensity = 2 units.
Attachment:
GMAT-Club-Forum-e33ipien.png [ 12.12 KiB | Viewed 1922 times ]
General Discussion
25 Dec 2025, 09:44
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Intensity is inversely proportional to distance^2 from source
Let x is a constant
I=x/(d^2)
x= I.d^2
When d=6, i is 8 units
x= 8*(6^2)=288
Check given options
If d=4...Intensity= 288/16=18
If d=12...Intensity= 288/144=2.......available in options
Distane= 12 and Intensity= 2
Let x is a constant
I=x/(d^2)
x= I.d^2
When d=6, i is 8 units
x= 8*(6^2)=288
Check given options
If d=4...Intensity= 288/16=18
If d=12...Intensity= 288/144=2.......available in options
Distane= 12 and Intensity= 2
