Final answer:
The expression 4(0.6)+2.5 is an estimate because it uses rounded figures of $0.60 for glue sticks and $2.50 for markers instead of the exact prices of $0.59 and $2.48. This makes the calculation easier but results in an approximation instead of the precise total cost of $4.84.
Step-by-step explanation:
The expression 4(0.6)+2.5 is an estimate rather than the exact cost of Uma's purchases because it involves rounding the prices of the items before performing the calculation. Specifically, the glue sticks were priced at $0.59 each but were rounded up to $0.60 each, and the set of markers was priced at $2.48 but was rounded up to $2.50 for the estimate. When calculating the total cost, using these rounded figures will give a close approximation rather than an exact total.
Using exact values, you would multiply 4 by $0.59 to get the precise cost of the glue sticks, which equates to $2.36. Then, you would add the exact cost of the markers, $2.48, resulting in a total of $4.84.
However, by rounding the prices, Uma is simplifying the arithmetic to make a quick and practical estimation of her total expenses, which may differ slightly from the actual amount.
It is useful to note that if the list of products were much longer, and we used more realistic prices, the total quantity spent over a year might be some messy-looking number like $17,147.51 or $27,654.92.