A car accelerates at a constant rate from zero to 37.8 m/s in 10 seconds and then slows to 13.5 m/s in 5 seconds. What is its average acceleration to the nearest tenth of a m/s2 during the 15 seconds?

Average acceleration

= (velocity change)/(time interval)
= (13.5 m/s)/15 s = 0.9 m/s^2