SAT Math Multiple Choice Question 761: Answer and Explanation
The scatterplot above charts the temperature (in degrees Kelvin) and luminosity (in Suns) for 50 stars, including our own sun, that fall under the category of "Main Sequence" stars.
According to the line of best fit shown on the scatterplot, a Main Sequence star with a temperature of 10,000°K is approximately how many times as luminous as a Main Sequence star with a temperature of 5,000°K?
- A. 9 times as luminous
- B. 90 times as luminous
- C. 900 times as luminous
- D. 900,000 times as luminous
Correct Answer: C
Advanced Mathematics (rational equations) MEDIUM-HARD
The line of best fit appears to cross the points (10,000°K, 102 suns) and (5,000°K, 10-1 suns), give or take a small error. This means that a Main Sequence star with a temperature of 10,000°K is about 102 ÷ 10-1 = 103 = 1,000 times as bright as a Main Sequence star with a temperature of 5,000°K. Choice (C) 900 is the only choice within an acceptable margin of error.