SOLUTION: There are several elevators in the Sandy Beach Hotel. Each elevator can hold at most 12 people. Additionally, each elevator can only carry 1600 pounds of people and baggage for saf

Algebra ->  Graphs -> SOLUTION: There are several elevators in the Sandy Beach Hotel. Each elevator can hold at most 12 people. Additionally, each elevator can only carry 1600 pounds of people and baggage for saf      Log On


   



Question 1202250: There are several elevators in the Sandy Beach Hotel. Each elevator can hold at most 12 people. Additionally, each elevator can only carry 1600 pounds of people and baggage for safety reasons. Assume on average an adult weighs 175 pounds and a child weighs 70 pounds. Also assume each group will have 150 pounds of baggage plus 10 additional pounds of personal items per person.
Part A. Write a system of linear equations or inequalities that describes the weight limit for one group of adults and children on a Sandy Beach Hotel elevator and that represents the total number of passengers in a Sandy Beach Hotel elevator.
Part B. Several groups of people want to share the same elevator. Group 1 has 4 adults and 3 children. Group 2 has 1 adult and 11 children. Group 3 has 9 adults. Which of the groups, if any, can safely travel in a Sandy Beach elevator?

Answer by math_tutor2020(3817) About Me  (Show Source):
You can put this solution on YOUR website!

Part A

We focus on one elevator only.

x = number of adults
y = number of children
These variables are nonnegative integers 0,1,2,3,...

The elevator allows at most 12 people meaning that
x%2By+%3C=+12
Either x+y < 12, or x+y = 12

Now to the weight requirements.

Each adult weighs 175 pounds on average.
Add on 10 pounds of their personal belongings to see that each adult contributes a weight of 175+10 = 185 pounds.
x number of adults contribute 185x pounds

Each child weighs 70 pounds on average.
That bumps up to 80 pounds when considering their personal luggage.
Therefore, y number of children adds on 80y extra pounds.

The total weight so far is 185x+80y pounds.
Then add on the 150 pounds of luggage mentioned in the instructions.
This is the publicly shared luggage of the group (as opposed to the personal luggage).

Therefore, the total combined weight of each person and all luggage (personal or shared) is 185x+80y+150 pounds.

This total cannot exceed 1600 pounds.
This is the ceiling value.
Since we're dealing with an elevator, it is fitting to think of a hypothetical tower with 1600 floors as the highest we can go.
Feel free to come up with other metaphors.

This leads to the inequality 185x%2B80y%2B150+%3C=+1600
I'll let the student solve for y if the teacher requires it.

To recap everything we have these two inequalities
system%28x%2By+%3C=+12%2C185x%2B80y%2B150+%3C=+1600%29
that represent the system of inequalities

A more narrowly defined system would be
system%28x%2By+%3C=+12%2C185x%2B80y%2B150+%3C=+1600%2Cx+%3E=+0%2Cy+%3E=+0%29
which prevents x and y from being negative.
It makes no sense to have a negative number of people.

================================================================================

Part B

Group 1 has 4 adults and 3 children.
x = 4
y = 3

Plug those into the 1st inequality
x%2By+%3C=+12
4%2B3+%3C=+12
7+%3C=+12
The 1st condition is satisfied.

Do the same for the other inequality
185x%2B80y%2B150+%3C=+1600
185%2A4%2B80%2A3%2B150+%3C=+1600
1130+%3C=+1600
The 2nd condition is satisfied as well.

Both conditions have been met.
Group 1 can board the elevator.

--------------------

Group 2 has 1 adult and 11 children.
x = 1
y = 11

x%2By+%3C=+12
1%2B11+%3C=+12
12+%3C=+12
That works out

185x%2B80y%2B150+%3C=+1600
185%2A1%2B80%2A12%2B150+%3C=+1600
1295+%3C=+1600
That works as well.

Group 2 can board the elevator.
--------------------

Group 3 has 9 adults
x = 9
y = 0

x%2By+%3C=+12
9%2B0+%3C=+12
9+%3C=+12
That works out

185x%2B80y%2B150+%3C=+1600
185%2A9%2B80%2A0%2B150+%3C=+1600
1815+%3C=+1600
The last inequality is false, so condition #2 is NOT met

The extra weight is 1815-1600 = 215 pounds


Group 3 is NOT safely allowed to board the elevator.
--------------------


Summary:

Groups that can board a single elevator:
Group 1
Group 2

Group 3 is NOT safely allowed to board a single elevator.
Group 3 will have to split up in some way. At least two people must leave the elevator.