Sometimes making slight changes to the scenario can make a difference, and sometimes it does not.
Changes can be made to the following parameters:

• Quantities
  Example: When you go shopping at Publix you can buy a single bottle of water for $1 or a six-pack of identical bottles for $4 for a cheaper unit price. However, when you fill up for gas it is the same unit price whether you buy 1 gallon or 16 gallons of gas.

• The time scale (longer or shorter)
  Ratios, for example if you drive twice as long at a constant speed. Be careful because realistically you might have to stop to buy more fuel, bathroom breaks, eat, etc. 

• Prices (discounts/markups)
  Example: individuals can buy a small pack of markers, but schools can buy much larger quantities at a discount. 

• Tariffs (taxes)
  Example: New tariffs on imported goods from a country result in higher prices and possibly less people buying them

• The law

Examples: (1)Laws that require seat belts have saved an estimated 15,000 lives in the US in 2007. (2) Laws that require bike helmets result in fewer people riding bikes.

• As well as others

Example: extending graphs drawn from data you have collected. If you have a years worth of data showing a positive correlation and average increase of 50 sales per month you can make predictions about the following year from the pattern.

Let’s take a look at the example activity from the Cambridge International AS & A Level Thinking Skills Coursebook.

Example Activity 12.1:

Abigail runs 100 m in 11 seconds, whereas Ella runs 200 m in 23 seconds. They maintain these speeds for a race of 1 km. Who wins and by how many seconds?

What is the problem with the scenario in this question? Are the numbers in the question realistic?