Project ForgeHari (H), Gita (G), Irfan (I) and Saira (S) are siblings (i.e. brothers and sisters). All were born on 1st January. The age difference between any two successive siblings (that is born one after another) is less than 3 years. Given the following facts: (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
Since all are born on 1st January with distinct birth years (no twins), adjacent age gaps in any birth-order permutation are positive integers less than 3 (i.e. 1 or 2). Testing SGHI (S oldest, then G, H, I youngest): the Gita-Saira gap is the adjacent gap g1=1 (satisfies fact ii exactly), and fact (i) requires H+G > I+S, which reduces to the third gap (H to I, via S-G-H-I) exceeding 1 — achievable with g1=1, g2=1, g3=2 (e.g. ages 10,9,8,6 for S,G,H,I: H+G=17 > I+S=16, and |G-S|=1). Checking the other three options: HSIG and IGSH both require impossible negative total gap sums to satisfy fact (i), and IGSH's Gita-Saira gap of 2 ranks apart can't force the needed inequality either — SGHI is the only order consistent with every fact.
Source: GATE ME 2010 (2010)
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