Mr. Joyce, the school librarian, is ordering new keyboards and mice for all of the school's computer labs. Each keyboard costs $13.50, and each mouse costs $6.50. There are 3 computer labs in the school, and each computer lab has s computer stations.
Pick all the expressions that represent how much Mr. Joyce will spend on new keyboards and mice.
3(13.50s+6.50s)
20.00s+3
(13.50s+3)+(6.60s+3)
3(20.00s)
To find out how much Mr. Joyce will spend on keyboards and mice, we need to calculate the total cost for one lab and then multiply it by the number of labs (which is 3). Given that there are "s" computer stations in each lab, we can calculate the total cost for keyboards and mice in one lab and then multiply it by 3 for all labs.
The cost for keyboards for one lab is 13.50 per keyboard times s keyboards: \( 13.50s \).
The cost for mice for one lab is 6.50 per mouse times s mice: \( 6.50s \).
Adding these two costs will give us the total cost for one lab:
\[ 13.50s + 6.50s \]
Simplifying that sum gives us the cost for all keyboards and mice in one lab:
\[ 20.00s \]
Now, we multiply that cost by the number of labs (3) to get the total cost for all labs:
\[ 3 \times (20.00s) \]
The possible correct expressions that represent the total cost are:
1. \( 3(13.50s + 6.50s) \) - This is correct because it represents the sum of the cost for all keyboards and mice in one lab, multiplied by the number of labs.
2. \( 3(20.00s) \) - This is also correct because it is another way to express the total cost after simplifying the per-lab sum.
The other two expressions are incorrect for the following reasons:
1. \( 20.00s + 3 \) - This expression adds 3 to the cost of s computer stations and does not account for the cost of keyboards and mice for all 3 labs.
2. \( (13.50s + 3) + (6.60s + 3) \) - This expression incorrectly adds a flat number (3) to the cost of each item, and the cost per mouse is incorrect it should be 6.50s, not 6.60s.
Therefore, the correct expressions that represent how much Mr. Joyce will spend on new keyboards and mice are:
- \( 3(13.50s + 6.50s) \)
- \( 3(20.00s) \)