#### Answer

(a) The average speed is $1.74~m/s$
(b) The average velocity is $0.332~m/s$

#### Work Step by Step

(a) We can find the time it takes to swim the first $50.0~m$:
$t = \frac{d}{v} = \frac{50.0~m}{1.84~m/s} = 27.17~s$
We can find the time it takes to swim the next $34.0~m$ in the opposite direction:
$t = \frac{d}{v} = \frac{34.0~m}{1.62~m/s} = 20.99~s$
We can find the average speed:
$average~speed = \frac{distance}{time}$
$average~speed = \frac{50.0~m+34.0~m}{27.17~s+20.99~s}$
$average~speed = 1.74~m/s$
The average speed is $1.74~m/s$
(b) We can find the average velocity:
$average~velocity = \frac{displacement}{time}$
$average~velocity = \frac{50.0~m-34.0~m}{27.17~s+20.99~s}$
$average~velocity = 0.332~m/s$
The average velocity is $0.332~m/s$