ECON 303 Lecture : Tutorial Activity 2 - Assignment 2

Discuss how higher taxes can affect the incentives for workers as well as for entrepreneurial activity.

Here is my assignment. I need help with Scenario 2 & 3. Thanks!

I have attached the whole assignment into 2 parts in the attachments. 

A math camp instructor estimates that students will take 3 hours to complete the first assignment of math puzzles, but will be able to improve at a rate of 0.95 for the second assignment (they will take 5% less time). If they are able to sustain this rate of improvement, how long will students take to complete the fourth assignment.