February 1993 LSAT Section 1 Question 16

Comets do not give off their own light but reflect light from other sources, such as the Sun. Scientists estimate the...

Elizabeth25 on October 26 at 03:40AM

clarity on b

how were the estimates too low? if it was 60 times less light per unit shouldn't answer b have said that the previous estimates were too high. what am I missing here.

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Emil-Kunkin on October 27 at 09:35PM

I personally hate questions like this about proportionality, so I like to use examples.

Let's imagine that the comet has a brightness level of 10, and from that, we calculate that the mass is 100.

This is operating on the assumption that the mass/brightness ratio is 10/1. That is, for every unit of brightness, the mass increases by ten units.

Now, imagine that we found out that the relationship between mass and brightness we though we knew was wrong. It turns out that the comet actually "should" be 60 times brighter than it actually is. So, if we want to figure out its mass, we need to also multiply that by 60. The 10/1 ratio would still hold, but the observed brightness isn't what matters, what we need to use for the calculation would be what the brightness should be, or 600. This would mean the true mass would be 6,000. So, this means the earlier estimates were too low.

Elizabeth25 on November 6 at 06:46AM

makes sense thank you emil