Question

the north american x - 15 rocket - powered aircraft is the world’s fastest manned plane on record. it travels about 7×10³ kilometers per hour. the duck hawk is the world’s fastest bird, traveling at speeds over 3×10² kilometers per hour. about how much faster is the plane? im still not sure. less than 20 times faster exactly 20 times faster more than 20 times faster

Explanation:

Step1: Set up division for speed - comparison

To find out how many times faster the plane is than the bird, we divide the speed of the plane by the speed of the bird. The speed of the plane is $7\times10^{3}$ km/h and the speed of the bird is $3\times 10^{2}$ km/h. So the calculation is $\frac{7\times10^{3}}{3\times10^{2}}$.

Step2: Use exponent - division rule

According to the rule $\frac{a\times10^{m}}{b\times10^{n}}=\frac{a}{b}\times10^{m - n}$, we have $\frac{7}{3}\times10^{3 - 2}=\frac{7}{3}\times10^{1}=\frac{70}{3}\approx23.33$.

Answer:

D. more than 20 times faster