Students at Warlock High are allowed to sign up for one social studies class each year. The numbers in each grade level signing
up for various classes for the next school year are given in the following table: Grade US History Civics World History Economics Total
10th 75 10 125 5 215
11th 130 85 75 60 350
12th 35 150 50 105 340
Total 240 245 250 170 905
Part A: What is the probability that a student will take Civics? (2 points)
Part B: What is the probability that a 10th-grader will take either US History or World History? (2 points)
Part C: What is the probability that a student will take Economics given that he or she is in the 10th grade? (2 points)
Part D: Consider the events "A student takes Civics" and "A student is a 12th-grader." Are these events independent? Justify your answer. (4 points)
part a: number of students taking civics/ total students= 245/905=0.2707
part b: students of 10th grade taking history/ total students+ students of 10th grade taking world history/total students= 75/905 + 125/905=200/905= 0.221
part c: number of students taking economics/total students of 10th grade= 5/215=0.0233
part d: This is not independent because there is a intersection of 12th grade and civics subjects we can use a formula also, if they are independent we can write
It’s 678m2 because Given the dimension of a rectangular prism l×b×h,its surface area is 2(lb+bh+lh)Hence surface area of a rectangular prism that measures 12 m x 11 m x9 mis 2×(12×11+11×9+12×9)= 2×(132+99+108)= 2×339=678m2