中二數學問題 - Ans.fyi 參考答案

中二數學問題

2007-08-08 11:19 pm

問題一.Chris takes 3hours 18 minute to complete a Marathon race this year . the time he needed is 12% less than that in last year. Find the time chris needed to complete the race last year.

問題二.in a garden, there were 350 red tulips and 250 white tulips. three months later,16% of the red tulip withered but white tulips were increased by 20%. find the percantage change of the total number of tulips.

回答 (1)

Hiu Tung

2007-08-08 11:38 pm

✔ 最佳答案

Question 1:
3 hours 18 minutes = 198 minutes
Let y be the time he needed to complete the race last year.
y* (1-12%) = 198
y* 88%=198
y=198/88%
y=225
Chris needed 225 minutes (3 hours and 45 minutes) to complete the race last year.

Question 2:
The no. of red tulip three months later
= 350*(1-16%)
= 350*84%
= 294
The no. of white tulips three months later
= 250*(1+20%)
= 250*120%
= 300
The percentage change of the total number of tulips
= (350+250-294-300)/(350+250)*100%
= 6/600*100%
= 1%

參考: Hope I can help you.

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