Please help me revise my answer using correct formula. It is about STATISTICAL INFERENCE FOR TWO SAMPLES

In Question no. 1, Here are my answers:

STATISTICAL INFERENCE FOR TWO SAMPLES This exercise will provide you the opportunity to apply the knowledge gained from the lectures about statistical inference for two samples. Using the data of Cervantes (2007), provide a comprehensive answer to the following: 1. Is there a difference between the performance of boys and girls in English? (Hint: Dichotomize the grade in English for the Second Grading of pupils from the two schools using 85 as basis and form the 2x2 contingency table) Answer: GENDER Mean Standard Deviation English grades BOYS 11 82.3636 .31909 GIRLS 17 83.1176 3.65517 Boy Girl Combined Boy 4 (3.54) 5 (5.46) 9 Girl 7 (7.46) 12 (11.54) 19 Total 11 17 28 Observed frequencies: 4 7 12 Expected frequencies: 3.54 5.46 7.46 11.54 1. Ho: There is no significant difference between the performance of boys and girls in English for the Second Grading period. Ha: There is a significant difference between the performance of boys and girls in English for the Second Grading period. 2. a = 0.05 3. Test Statistic and Critical Region: with df = (r-1) (k-1) = 1 at 0.05 level is 3.841 (base on y table) 4. Computations: x2 = (4-3.54) + (5-5.46)+ (7-7.46)+ (12-11.54) 3.54 5.46 7.46 11.54 = (0.46) + 3.54 = 0.0598 = 0.0598 + 0.0388 + 0.0284 + 0.0183 = (-0.46) = 5.46 = 0.0388 = 0.14534 = (-0.46)= = 7.46 = 0.0284 Conclusion: Since the computed y' is less than the critical value = (0.46) + 11.54 = 0.0183 of 3.841, the null hypothesis is accepted. Meaning, there is no significant difference between the performance of boys and girls in English for the Second Grading periodData: Performance of Grade VI pupils in two elementary schools in Mama North District (Cervantes, 2007) RESP GRADING SCHOOL SEX MATH ENGLISH AVERAGE 20 90 90_0 85 86.0 81 81.0 78 79_0 79 77 78.0 77 76 76.5 87 88.0 86 36.5 85 85.5 84 84.5 83 83.5 82 82.5 81 81.5 80.5 80.0 78 79_0 76 76.0 85 34.5 82 81.0 79 79_0 79 78.5 85 85.0 84 84.0 83 83_0 83 82.5 83 82.0 81 80.5 80 30_0 91 91.5 28 89_0 35 85.0 81 81.5 79 79_0 79 79_0 78 78.0 91 90 5 88.5 87 88.0 84 34.0 84 83.5 82 82.0 81 81.5 80 80.5 79 79 5 77 77.5 85 85.0 19 82.520 79 79 79_0 21 79 79 79_0 22 36 86.0 86 85.5 24 84 84.0 25 83.5 26 81 82.0 27 80 80.5 28 80 80.5 Coding: SCHOOL: 1 -Bagong Sicat E.S.; 2 -Estrella Village E.S. // SEX: 1 -boy; 2-girl