Final answer:
To find the total cost including tax for a $9.78 item with a 9.5% sales tax, convert the tax rate to a decimal (0.095), multiply by the price to get the tax amount ($0.93), and add it to the original price for a total of $10.71.
Step-by-step explanation:
To calculate the total cost including a 9.5% sales tax for an item priced at $9.78, first you need to convert the percentage to a decimal. This is done by dividing the percentage by 100. Hence, 9.5% becomes 0.095. Next, calculate the amount of sales tax by multiplying the item's price by the tax rate: $9.78 × 0.095 = $0.9291. Round this to the nearest cent to get $0.93. Finally, add the original price of the item to the amount of sales tax: $9.78 + $0.93 = $10.71. So, the total cost of the item after tax is $10.71.