Based on the expenses that she spent on and the amount received, your friends Marginal Propensity to Consume is 0.1 or 10%.
Marginal propensity to consume can be found by the formula:
= Increase in consumption / Increase in income
The only consumption will be the $100 spent on the new grill.
MPC is:
= 100 / 1,000
= 10%
Find out more on Marginal Propensity to Consume at https://brainly.com/question/17930875.