※ 引述《zoo22 (zoo)》之銘言： : 3. Pqst is a rectangle pq=3 pt=6; r is a pt on qt such that area of trapezium : pqrt=12. what is the perimeter of trapezium pqrt? 題目怪怪的，r應該在qs上吧?? 如果r在qs上，則可從梯形面積求出qr=2, rs=4 又可從直角三角形trs求出 tr=5 則梯形邊長 = qp + pt + tr + rq = 3 + 6 + 5 + 2 = 16 : 4. Which of the following is both the mean and the median of 7 consecutive : integer so that the least of which is x. : A. x+4 : B. x+3 : C. x+2 : D. x+28/7 : E. x+3/2 七個連續整數，所以是 x x+1 x+2 x+3 x+4 x+5 x+6，mean = median 答案是x+3 : 8. John traveled 80% of the way from Yellow-town to Green-fields by train : at an average speed of 80 miles per hour. The rest of the way John : traveled by car at an average speed of v miles per hour. If the average : speed for the entire trip was 60 miles per hour, what is v in miles per : hour? : (a) 30 : (b) 40 : (c) 50 : (d) 55 : (e) 70 設整趟travel的總距離是D，則 v = 0.2D/[(D/60)-(0.8D/80)] 0.2D：剩下20%旅程的距離 (D/60)-(0.8D/80)：(整個旅程花的時間)-(前80%旅程花的時間)， 也就是剩下20%旅程所花的時間 如果覺得很複雜，其實可以隨便假設總距離是100，代進去算答案就出來了 答案是v=30 : 10.In a nationwide poll, N people were interviewed. If 1/4 of them answered : "yes" to question 1, and of those, 1/3 answered "yes" to question2, which : of the following expresions represents the number of people interviewed : who did not answer "yes" to both questions? : A : N/7 : B : 6N/7 : C : 5N/12 : D : 7N/12 : E : 11N/12 謝謝BlueKidds更正，是1/4的人中的1/3 say yes，所以答案是E囉 : 7. Out of 10 shirts, 2 are defective. 3 are selected, what is the : probabiltiy that none is defective? 8/10 * 7/9 * 6/8 = 7/15 --

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