Question

interpolar tres medios aritmeticos entre 31 y 69

Answer 1

Tenemos.

31. ---- .----. ----. 69  Nos queda la progresion de 5 terminos.
n = 5
a1 = 31
an = 69
d = ?

Formula.

an = a1 + (n- 1)d
69 = 31 + (5 - 1)d
69 - 31 = 4d
38 = 4d
38/4 = d  Simplificando
19/2 = d

1er termino = 31
2do termino = 31 + d = 31 + 19/2 = (62/2 + 19/2) = (62+19)/2 = 81/2
3er termino = 81/2 + 19/2 = (81 + 19)/2 = 100/2 = 50
4to termino = 100/2 + 19/2 = (100 + 19)/2 = 119/2

Respuesta.
La progresion queda:
31. 81/2 . 50 . 119/2 . 69