某学校运动会的立定跳远和\(30\)秒跳绳两个单项比赛分成预赛和决赛两个阶段\(.\)下表为\(10\)名学生的预赛成绩,其中有三个数据模糊.
学生序号 | \(1\) | \(2\) | \(3\) | \(4\) | \(5\) | \(6\) | \(7\) | \(8\) | \(9\) | \(10\) |
立定跳远\((\)单位:米\()\) | \(1.92\) | \(1.96\) | \(1.78\) | \(1.76\) | \(1.74\) | \(1.72\) | \(1.80\) | \(1.82\) | \(1.68\) | \(1.60\) |
\(30\)秒跳绳\((\)单位:次\()\) | \(63\) | \(a\) | \(75\) | \(60\) | \(63\) | \(72\) | \(70\) | \(a-1\) | \(b\) | \(65\) |
在这\(10\)名学生中,进入立定跳远决赛的有\(8\)人,同时进入立定跳远决赛和\(30\)秒跳绳决赛的有\(6\)人,则\((\) \()\)