diff --git a/source/_posts/answer6.md b/source/_posts/answer6.md
index 8d0d546..1d1dda3 100644
--- a/source/_posts/answer6.md
+++ b/source/_posts/answer6.md
@@ -195,6 +195,7 @@ int main()
 #include <stdio.h>
 
 double score[5][3];
+double average[5];
 
 void Average_Student(void)
 {
@@ -204,6 +205,7 @@ void Average_Student(void)
             avg += score[i][j];
         }
         avg /= 3;
+        average[i] = avg;
         printf("第%d个学生的平均成绩是%f\n", i + 1, avg);
     }
 }
@@ -240,13 +242,11 @@ void Calc_Var(void)
 {
     double sum_xi = 0;
     double sum_xi2 = 0;
-    for (int i = 0; i < 3; ++i) {
-        for (int j = 0; j < 5; ++j) {
-            sum_xi2 += score[i][j];
-            sum_xi2 += score[i][j] * score[i][j];
-        }
+    for (int i = 0; i < 5; ++i) {
+        sum_xi += average[i];
+        sum_xi2 += average[i] * average[i];
     }
-    double sigma = sum_xi2 / 15 - sum_xi * sum_xi / 225;
+    double sigma = sum_xi2 / 5 - sum_xi * sum_xi / 25;
     printf("方差是%f\n", sigma);
 }