By observing the marks scored by 40 students in the test, we can construct the
table as follows.
(a) The students who obtained their marks equal to or more than 7 are the students who
obtained their marks as either of 7, 8, and 9. Hence, number of these students — 5 + 4 + 3= 12
(b) The students who obtained their marks below 4 are the students who
obtained their marks as either of 1, 2, and 3.
Hence, number of these students = 2 + 3 + 3 = 8