Question

an astronomical unit (au) is equal to the average distance from the sun to earth. answer parts a and b.
a. an astronomical unit is about 92,955,807 miles. use a single digit times a power of ten to estimate this value to the nearest ten million miles.
□×10^□ miles
(type whole numbers.)
b. venus is about 7.2×10^(-1) au from the sun. mars is about 1.5 au from the sun. which planet is closest to earth?
venus
mars

Explanation:

Step1: Round 92,955,807 to nearest ten - million

92,955,807 is closer to 90,000,000.

Step2: Write in scientific - notation

90,000,000 can be written as $9\times10^{7}$.

Step3: Calculate distances from Earth

Earth is 1 AU from the Sun. Distance between Earth and Venus: $|1 - 0.72|= 0.28$ AU. Distance between Earth and Mars: $|1.5 - 1| = 0.5$ AU.

Step4: Compare distances

Since $0.28<0.5$, Venus is closer to Earth.

Answer:

a. $9\times10^{7}$
b. Venus