Project ForgeHari (H), Gita (G), Irfan (I) and Saira (S) are siblings (brothers and sisters). All were born on 1st January. The age difference between any two successive siblings (born one after another) is less than 3 years. Given: i. Hari's age + Gita's age > Irfan's age + Saira's age. ii. The age difference between Gita and Saira is 1 year. However, Gita is not the oldest and Saira is not the youngest. iii. There are no twins. In what order were they born (oldest first)?
- AHSIG
- SGHI
- CIGSH
- DIHSG
Explanation
Testing order S,G,H,I (oldest to youngest): S-G gap of 1 year satisfies both the successive-gap constraint and fact ii's |G-S|=1 directly (S oldest, so not youngest ✓; G second, so not oldest ✓). For fact i (H+G>I+S), assigning ages S=x, G=x-1, and letting the G-H gap be g1 and H-I gap be g2 (both positive integers <3), the inequality H+G>I+S simplifies to g2>1, satisfied by g2=2 — a fully consistent assignment exists. The other orderings can be shown to violate one of the given facts for every possible age assignment.
Source: GATE CS 2010 (2010)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.