Question

A swimming pool is 25 m long and 12 m wide. A single 4 m wide lane is roped off.
Ismaeel swims in the 4 m wide lane. Swimming two
lengths of the pool counts as one lap for Ismaeel.
Kosha swims on the other side of the roped off lane,
in the larger rectangular portion of the pool. A lap
for Kosha consists of swimming once around a circuit
that is 1/2 m away from each edge and 1/2 m away from the rope divider.
a) How much longer is Kosha’s lap than Ismaeel’s
lap?
b) Ismaeel and Kosha each complete ten laps.
Determine how much farther than Ismaeel that
Kosha swam.

Answer 1

Given :

Length of swimming pool = 25m

Width of swimming pool = 12m

Width of roped off lane = 4m

To Find :

a) How much longer the lap of Kosha compared to Ismaeel.

b) How much far did Ismaeel swam compared to Kosha.

Solution :

a)

The large rectangular part of the pool is  12−4 = 8 m wide.

Since Kosha swims $\frac{1}{2}$ m from the ‘edges’, Kosha swims around a rectangle that is

8− 1 2 − 1 2 = 7 m wide

and

25− 1 2 − 1 2 = 24 m long.

The total distance Kosha swims in one lap is

24 + 7 + 24 + 7 = 62m.

Ismaeel swims 25 + 25 = 50m in two lengths, or one lap.

Thus Kosha’s lap is 62−50 = 12m longer than Ismaeel’s lap.

b)

In ten laps, Kosha swims

10×62 = 620m

while ,

Ismaeel swims

10×50 = 500m.

So Kosha swims

620−500 = 120m further.

Alternatively:

Since in each lap Kosha swims 12m further, in 10 laps

she swims 10×12 = 120m further.