Paul went to his friend's 2 km from his house, he used his bike and took him 9 minutes. Paul and his friend rode another 1.5 km to get some ice cream, it took them 10 minutes.
What was Paul's average speed of the whole trip?

What does the process of natural selection involve

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?

Scientists often have to deal with numbers that are either very large or very small. for example, the radius of the sun is approximately 696,000 kilometers, while bacterial cells are as small as 1.9 × 10-4 millimeters. express each number in an alternate form.