This problem is from the 2015 Senior Mathematical Challenge published by the UKMT.
A fiendishly difficult problem
Impossible maths problem? Not so hard!
Here is an interesting article on a maths question many Australian High School students were complaining about. I think that the question is rather contrived and therefore I would have avoided setting it. It’s not totally impossible though. It relies on knowledge that the median is the middle line in the box plot so that the mean can be calculated. Now you also need to calculate the regression line gradient so that requires knowing a point on the graph. This point is therefore (22 – 0.525, 684/20) i.e. (mean of x, mean of y).
b is therefore 2.0864 and using a value of x = 19, we find that y = -10.6063 + 2.0864 x 19 = 29 chirps per minute (to the nearest whole number).
https://interestingengineering.com/high-school-cricket-math-question-stumps-the-internet
If you are looking at ways to improve your understanding of mathematics, I can recommend some resources.