Answer: 1150%
Step-by-step explanation: To calculate the percentage increase in price we apply the formula:
Percentage change = [100 (New selling price/cost - Old price/cost)] / 100
New cost = $1250
Old cost = $100
Therefore, percentage change = [100 (1250 - 100)] / 100
(100 x 1150) / 100 = 1150%
Price increased by 1150% from $100 to $1250.