Arranging the data in ascending order, we get 17, 18, 23, 25, 29, 31, 35, 35, 35, 37, 38, 42
(a) Range – Highest value – Lowest value = 42 – 17 = 25
(b) Mean = Sum of all observations/ Number of observations
= (17+18+23 +25+ 29+31+35+35+37+38+42)/12
= 365/12
= 30.41
(c) Observations are even in number.
∴ Median = Mean of two middle most observations
= (31 +35)/2
= 66/2
= 33
(d) Since, 35 occurs most frequently i.e., 3 times.
∴ Mode = 35.