Partal Variations

2007-03-04 7:31 pm

The school soccer team organise a 4-day soccer training camp.The school subsidizes two-third of the total expenses and the team members share thr remaining expenses.The total expenses ＄E for the camp is partly constant and partly varies directly as the number of team members joining the camp N.
If 15 members join the camp, the school has to pay ＄2400;
If 20 members join the camp, the school has to pay＄3000.
(a) What is the total expenses if 20 members join the camp?

更新1:

(b) Express E in terms of N. (c)If 30 members join the camp, how much should each member pay? (d) If each members pays＄72, how many team members are there in the camp?

回答 (1)

netnet

2007-03-04 7:53 pm

✔ 最佳答案

a)
total expense = 3000 (3/2) = $4500

b)
let E = k + hN where k and h are constants
2400 = ( k + 15h)(2/3) ------(i)
3000 = (k + 20h) (2/3) ------(ii)
solve (i) and (ii) gives h=180 and k = 900
so , E = 900 + 180N

c)
total expense = 900 + 180(30) = $6300
each member should pay 6300(1/3) (1/30) = $70

d)
If each members pays＄72
72N(3) = 900 + 180N
N = 25
25 team members are there

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