In a year group of 63 students, 22 study Biology, 26 study Chemistry and 25 study Physics. 18 study both Physics and Chemistry, four study both Biology and Chemistry and three study both Physics and Biology. One studies all three subjects. How many students study: a. Biology only b. Physics or Chemistry c. none of Biology, Physics or Chemistry d. Physics but not Chemistry?
Ezequiel's Biology marks are 8.3, 6.8 and 9.4 out of 10. His final grade in Biology is the mean of these three marks. a. Calculate Ezequiel's final grade in Biology. Ezequiel wrote the three marks correct to the nearest unit to find his final grade in Biology. b. Calculate the final grade that Ezequiel found. c. Calculate the percentage error made by Ezequiel when finding his final grade in Biology.