Time, speed, distance - linear race( solved example - 9 ) #this question is of arithmetic .

There was a calculation typo here, we've put this annotation. Due to this, the time will also be 50 and 60 seconds instead.

Here's a newer solution:

Step 1: Find A's time

$t_A = \frac{400}{8} = 50 \text{ seconds}$

Step 2: Find B's time

$t_B = 50 + 10 = 60 \text{ seconds}$

Step 3: Use inverse proportionality (same distance, so speed and time are inversely proportional)

$\frac{v_A}{v_B} = \frac{t_B}{t_A} = \frac{60}{50} = \frac{6}{5}$

Step 4: Solve for B's speed

$\frac{8}{v_B} = \frac{6}{5}$

$v_B = \frac{8 \times 5}{6} = \frac{40}{6} = \boxed{\dfrac{20}{3} \text{ m/s}}$