GRE考试

【单选题】In 1950 Roberto was four times as old as Juan. In 1955 Roberto was three times as old as Juan. How old was Roberto when Juan was born
A、5
B、10
C、20
D、30
E、40
网考网参考答案：D
网考网解析：
Make a table to determine Roberto’s and Juan’s ages. Let x represent Juan’s age in 1950, and fill in the table as shown. \r\n \r\n \r\n 1950 \r\n 1955 \r\n \r\n \r\n Roberto \r\n 4x \r\n 4x+5 \r\n \r\n \r\n Juan \r\n x \r\n x+5 \r\n \r\n In 1955, Roberto was 3 times as old as Juan, so [*] Therefore, in 1950, Juan was 10 and Roberto was 40. Because Roberto is 30 years older than Juan, Roberto was 30 when Juan was born. document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>