To find the diameter, you use the formula: 2x. we use 2x because the radius is 2 times the diameter.

so, if the radius is 3,980, then we substitute that into the formula.

2(3,980)

this will give us 7960. the diameter is 7960 miles.

3 0

3 years ago

Julia can finish a 20-mile bike ride in 1.2 hours. Katie can finish the same bike ride in 1.6 hours. How much faster does Julia

Nimfa-mama [501]

We know that, $speed = \frac{distance}{time}$

Julia can finish a 20-mile bike ride in 1.2 hours.

The distance Julia travels is 20 miles and the time she takes is 1.2 hours.

So, Julia's speed = $\frac{20}{1.2}$ = 16.67 mph

Katie can finish the same bike ride in 1.6 hours.

The distance Katie travels is 20 miles and the time she takes is 1.6 hours.

So, Katie's speed = $\frac{20}{1.6}$ = 12.5 mph

Now, to find how much faster Julia rides than Katie we subtract Katie's speed from Julia's speed.

So, 16.67 mph - 12.5 mph = 4.17 mph = 4.2 mph (approximately)

Thus, Julia rides 4.2 mph faster than Katie.

5 0

3 years ago

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