In order to study the relationship between the amount of sleep a student gets and his or her school performance, a researcher collected data from 120 students. The two-way frequency table shows the number of students who passed and failed an exam and the number of students who got more or less than 6 hours of sleep the night before. <span>The probability that a student who failed the exam got less than 6 hours of sleep can be calculated as: </span> Let, L be the event of getting less than 6 hours of sleep F be the event of failing the exam. Then, P(L and F) = n(L∩F) ÷ n(F) = (10 ÷ 18) × 100% = 5 ÷ 9 × 100% = 55.55%
Add all the numbers up but pay attention you are counting 6.30 twice. then you divide by the numbers of days you have.(5) <span>Your answer should be 5.47</span>