Help with this relatively hard (impossible) question...

I have a question given to me by a friend who claims to have taken it from a BMAT paper which relatively seems impossible due to lack of information. I would like anyone to give me the answer to this question:

(Q)

A girl walks from her house to the pool at 6 km/hr. The distance between her pool and her house is unknown. A boy lives somewhere and reaches the pool exactly when she reaches.

The next day, she goes to the library which is located after the pool, 20 minutes late. When she reaches the pool, the boy is not there yet when she reaches the library he is there (exactly when she is there). The distance between the pool and the library is 3 km.

Find out the speed of the boy.

Here is a diagram which shows the girl's journey; to help you:

Notes and assumptions:

(1) The girl and boy are travelling at constant speed.

(2) On both days their speeds are same and constant i.e. On the second day, the girl is travelling at 6 km/hr

Note by Syed Hamza Khalid
2 weeks, 6 days ago

MarkdownAppears as
*italics* or _italics_ italics
**bold** or __bold__ bold
- bulleted- list
• bulleted
• list
1. numbered2. list
1. numbered
2. list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1paragraph 2

paragraph 1

paragraph 2

[example link](https://brilliant.org)example link
> This is a quote
This is a quote
    # I indented these lines
# 4 spaces, and now they show
# up as a code block.

print "hello world"
# I indented these lines
# 4 spaces, and now they show
# up as a code block.

print "hello world"
MathAppears as
Remember to wrap math in $$...$$ or $...$ to ensure proper formatting.
2 \times 3 $$2 \times 3$$
2^{34} $$2^{34}$$
a_{i-1} $$a_{i-1}$$
\frac{2}{3} $$\frac{2}{3}$$
\sqrt{2} $$\sqrt{2}$$
\sum_{i=1}^3 $$\sum_{i=1}^3$$
\sin \theta $$\sin \theta$$
\boxed{123} $$\boxed{123}$$