The fourth and sixteenth term of an A.P are 4 and 23 respectively. Then the tenth term of the A.P. is
13.5
Let a and d be the first term and common difference of the A.P.
a + 3d = 4
a + 15 d =23
Adding both the equations we get 2a + 18d = 27
a + 9d = 13.5