Answer: approximately 9.3 * 10^7 miles
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Step-by-step explanation:
x = distance from sun to earth
y = distance from sun to neptune = 2.8 * 10^9 miles
"earths distance from the sun is about 30 times shorter" compared to neptune's distance, so,
y = 30x
x = y/30
x = (2.8 * 10^9)/30
x = (2.8 * 10^9)/(3.0 * 10^1)
x = (2.8/3.0) * (10^9/10^1)
x = 0.933333333333333 * 10^(9-1) ... which is approximate
x = 0.933333333333333 * 10^8
x = 0.93 * 10^8 .... see note1 below
x = (9.3 * 10^(-1)) * 10^8 ... see note 2 below
x = 9.3 * (10^(-1)*10^8)
x = 9.3 * 10^(-1+8)
x = 9.3 * 10^7
Notes:
- note1: For this step, I rounded to 2 significant figures as the given distance 2.8 * 10^9 is in two sig figs.
- note2: we have 0.93 = 9.3 * 10^(-1) to help convert to scientific notation. The coefficient must be between 1.0 and 9.9
- note3: 9.3 * 10^7 = 93,000,000 = 93 million
- note4: I'm writing the answer in scientific notation to keep it consistent with the scientific notation 2.8 * 10^9