Bunuel
The distance between Mercury and Earth changes due to the orbits of the planets. When Mercury is at its closest point to Earth, it is 48 million miles away. When Mercury is at its furthest point from Earth, it is 138 million miles away. For a science project, Ruby calculates the maximum and minimum amount of time it would take to travel from Earth to Mercury in a spacecraft traveling 55 miles per hour. Approximately what are the times, in days?
(A) 3,636 and 10,454
(B) 14,545 and 41,818
(C) 36,364 and 104,545
(D) 87,272 and 250,909
(E) 872,727 and 2,509,091
These answer choices are really far apart.
Estimate. Shortest distance is 48 million miles
48 million = \(48 * 10^6\) miles
Greatest distance is 138 million miles
138 million = \(138 * 10^6\) miles
(1) Find miles per
dayCalculating (55 mph * 24 hours) is neither quick nor necessary. Change 55 mph, thus:
55 mph \(\approx\) 50 mph
Approximate miles per day?
\(\frac{50miles}{1hour}*\frac{24hours}{1 day}\approx\frac{1,200miles}{1day}\)
\(1,200 = 12 * 10^2\) miles per day
(2) Find time needed for shortest distance
\(t=\frac{D}{r}\)
\(t_1=\frac{48*10^6}{12*10^2}=\)
\((4*10^{(6-2)})=(4*10^4)=40,000\) days
Look at answer choices for something close
Answer C, time for shortest distance: 36,364
-- 40,000 is close to 36,364
-- Both are in the ten thousands
-- No other answer's time for shortest distance is close to 40,000
Answer C
(3) Doubt? Find the time needed to cover the greatest distance
Greatest distance: \(138 * 10^6\) miles
Adjust \(138\) to a multiple of \(12\)
\(138\approx132\)Time needed for greatest distance?
\(t_2=(\frac{132*10^6}{12*10^2})=\)
\((11*10^{(6-2)})=(11*10^4)=110,000\) days
Compare these answers to answer choices.
Time in days, fewest and most:
These) 40,000 and 110,000
Ans. C) 36,364 and 104,545
The other answers are not close at all.
Answer C