Final answer:
To round off the number of seconds in an hour to 1 significant figure, we round up the first significant figure by increasing it by 1. Therefore, the number of seconds in an hour rounded to 1 significant figure is 5000. Then, using the rounded speed of 200 mph, we can estimate that the plane takes approximately 720 seconds to travel 1 mile.
Step-by-step explanation:
To round off the number of seconds in an hour to 1 significant figure, we need to look at the first significant figure in the original value, which is 4. Since the digit to its right is greater than or equal to 5, we round up the first significant figure by increasing it by 1. Therefore, the number of seconds in an hour rounded to 1 significant figure is 5000.
Now, to work out an estimate for the number of seconds the plane takes to travel 1 mile, we need to use the rounded speed of 200 mph. Since 1 hour is equal to 3600 seconds, we can set up the following proportion:
200 mph = x seconds per mile
1 hour = 3600 seconds
Using cross-multiplication, we get:
x = (200 mph * 3600 seconds) / 1 mile
Simplifying the expression, we find that the plane takes approximately 720 seconds to travel 1 mile.