1. The distribution of score obtained by a sample of 18 candidates who took professional examination last year is as follows; Scores 10- 19 20-29 30-49 50-69 70-79 80-89 No. of 2 3 5 4 2 2 weeks Estimate the 90% Confidence limit on the marks scored by all candidates. Who took the examination assuming the scores are approximately normally distributed. 2. A college admission board of MOUAU is interested in estimating the difference between the means grade point average of students from two secondary schools. Independent random samples of students at the two secondary schools provided the result below. Government College Ibeku high school n1=23 12=26 X1=2.72 X2=3.02 S1=0.45 $2=0.38 Develop a 90% and 95% confidence interval for the difference between the two population means