1. x is greater than y by 5, and the sum of x and y is less than 49. Find the largest value of x is an integer.
2. The sum of three consecutive even numbers is greater than29. Find the least value of the smallest number.
3. In a History test, 5 marks are given for wach correct answer and 2 marks are deducted for each incorrect answer. Roger has answered 30 questions and his score is greater than15 marks. Find the least number of number of questions he has answered correctly.
f.2 maths 20分
2008-02-29 5:00 am
回答 (2)
2008-02-29 5:15 am
✔ 最佳答案
(1) x-y = 5-> x-5=y
x+y < 49
-> x+x-5 <49
-> 2x-5 < 49
-> 2x < 49+5
-> 2x < 54
-> x < 27
-> the largest value of x as an integer = 26
(2) Let the smallest even no. be x
x + (x+2) + (x+4) > 29
-> 3x + 6 > 29
-> 3x > 23
-> x>7.66
-> the least value of x = 8
(3) Let the least no. of correct answers be x
5x -2(30-x) >15
-> 5x - 60 + 2x > 15
-> 7x - 60 > 15
-> 7x > 75
-> x > 10.71
-> the least number of questions he answered correctly = 10
參考: Veni - Vidi - Vici
2008-02-29 9:36 pm
peterchan7708第3題既最後答案應該係11,而唔係10
收錄日期: 2021-04-23 17:44:30
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