John runs 1.0 m/s at first and then accelerates to 1.6 m/s during the course of 4.5 seconds. What is the average acceleration

It is d, all the other ones say incorrect answer .

The purpose of a lab is to do your "expirements" the importance of the topic is so you can now what the story is about and the last one is because no one is me with my question ( what is 3 over 4 x - 9 = 27 maybe you can )

D. the index of refraction of the second medium is lower.