IBPS RRB Officer Prelims 14 Nov 2016 Shift 1 Paper

(1) Let the two-digit numberbe 10x + y,
According to the question,
10x+y–9=10y+x
⇒10x+y–10y–x=9
⇒ 9x – 9y = 9
⇒ x – y = 1   .... (i)
and ,

x+y

2

=7.5
⇒ x + y = 15   ... (ii)
On adding equations (i) and(ii),
2x = 16
⇒ x = 8
from equation (i),
8 – y = 1
⇒ y = 8 – 1 = 7
∴Required number
= 10 × 8 + 7 = 87