If you see a lightning stroke and then, 15 seconds later, hear the thunder, the lightning is about miles away

3.2 miles

Explanation:

We can assume that the light coming from the lightning reach instantaneously our eyes (because light travels very fast, ), so the time between the lightining and the hearing of the thunder is equal to the time that sound takes to each us.

Sound travels in air approximately at speed

v = 343 m/s

So the distance it covers in a time of t = 15 seconds is

And using the conversion from meters to miles,

1 mile = 1609 meters

we find

convex lenses are thicker at the middle. rays of light that pass through the lens are brought closer together (they converge). a convex lens is a converging lens. when parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).