1. A bus company has to send 240 students to a barbecue site. There are now 8 drivers, 4 mini-buses which can carry 16 people each, and 6 coaches which can carry 52 people each available. If x mini-buses and y coaches are used, write down all the constraints about x and y.
2. A farmer raises x pigs and y cows under the following constraints.
The total number of pigs and cows should be less than 10.
The number of cows should not be more than twice the number of pigs
Given the constraints are
x+y<10
y ≤ 2x
x and y are non-negative integers
If the profit of the selling a cow is 3 times that of selling a pig, how many livestocks of each type should the farmer raise to obtain the maximum profit?
3. A merchants buys 50 kg of grade A tea, 180kg of grade B tea and110 kg of grade C tea to prepare two tea mixtures P and Q. Mixture P is prepared by mixing grade B tea and grade C tea in the ratio of 3:1. Mixture Q is prepared by mixing grade A, grade B and grade C tea in the ratio of 1:2:2. If the merchant prepares x kg of mixture P and y kg of mixture Q, write down all the constraints about x and y.
跪求高手解答作者: 數痴夢王 時間: 2016-3-24 07:30 AM
3.
Mixture P B(3x/4) C(x/4)
Mixture Q A(y/5) B(2y/5) C(2y/5)
so the constraints are
y/5<=50
3x/4+2y/5<=180
x/4+2y/5<=110 作者: 數痴夢王 時間: 2016-3-24 07:33 AM
