Since 1 km is 100,000 cm there are 39,400 inches in a kilometer
One way to see if two ratios are proportional is to write them as fractions and then reduce them. If the reduced fractions are the same, your ratios are proportional.
You need to use the Pythagorean theory. a² + b² = c². So you would end up with 10²+10²=c². So, 10²=100, therefore you would end up with 200=c². In order to find the length of the hypotenuse, you need to find C. To do this, you need to undo the square and find the square root of 200 and C. So, you would get √200=√c² which would equal 14.1 inches. Then, if needed to check the answer, plug the 10,10,and 14.1 back into the a²+b²=c² and it should make the statement true.
5) The relation between intensity and current appears linear for intensity of 300 or more (current = intensity/10). For intensity of 150, current is less than that linear relation would predict. This seems to support the notion that current will go to zero for zero intensity. Current might even be negative for zero intensity since the line through the points (300, 30) and (150, 10) will have a negative intercept (-10) when current is zero.
Usually, we expect no output from a power-translating device when there is no input, so we expect current = 0 when intensity = 0.
6) We have no reason to believe the linear relation will not continue to hold for values of intensity near those already shown. We expect the current to be 100 for in intensity of 1000.
8) Apparently, times were only measured for 1, 3, 6, 8, and 12 laps. The author of the graph did not want to extrapolate beyond the data collected--a reasonable choice.
I'm guessing this is a slope problem, so the equation would be like this: y = mx + b where m is the slope and b is the y-intercept.

Using this,

Which is equal to,