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Answer key — speed ratios & mental maths

# Answer Working
1 14.0% 175 ÷ 1,250
2 10% 38 − 24 − 4
3 +18% EBIT 20 → 110 − 80 × 1.08 = 23.6
4 +25% EBIT 50 − 30 = 20 → 55 − 30 = 25
5 +2.9% 1.05 × 0.98 − 1
6 −4% 0.8 × 1.2 = 0.96
7 +150% 1 ÷ 0.4 − 1
8 ₹15.08 90.5 ÷ 6.0
9 −5% 10% × 50%
10 25% 25 lakh ÷ 100 lakh
11 ≈ $266 m ₹23,400 m ÷ 88
12 ≈ 6 years 72 ÷ 12 (exact: 6.1)
13 20.1% 2.5^(1/5) − 1
14 4.05× 1.15^10
15 16.6% (1,318 ÷ 612)^(1/5) − 1 = 2.154^0.2 − 1
16 1.728× 1.2³
17 5.7% (1.12⁵ × 30/40)^(1/5) − 1 = (1.762 × 0.75)^0.2 − 1
18 ₹567 1,000 ÷ 1.762
19 ₹1,000 bn (₹1 trillion) 1 crore = 10 million; 1 lakh crore = 10¹²
20 100 million 10 × 10 million
21 +17.75% −8.75 + 11.5 + 15
22 20% f* = p − q = 0.6 − 0.4
23 25.9× 390 ÷ 15.08
24 4% 1 ÷ 25
25 ₹2,498.7 Cr 2,340 + 140.5 + 18.2
26 13.7× 2,499 ÷ 181.9
27 2.61× 402 ÷ 154.1
28 16.7× P/E = P/B ÷ RoE = 2.5 ÷ 0.15
29 1.03% 4 ÷ 390
30 1.5 30 ÷ 20
31 10× 0.60 ÷ (0.12 − 0.06)
32 2.0× (0.18 − 0.06) ÷ (0.12 − 0.06)
33 5% 2% ÷ 40%
34 ₹100 10 ÷ 0.10
35 ₹142.9 10 ÷ 0.07
36 ≈ 14.3 years 1 ÷ (0.12 − 0.05)
37 −12.5% 0.07 ÷ 0.08 − 1
38 ≈ ₹3,632 Cr 243 ÷ 0.0669 (the Kaveri reference TV is ₹3,636 Cr on unrounded FCF)
39 9.1% 1 − 100 ÷ 110
40 11 Cr; 9.1% 300 ÷ 300 = 1 Cr new shares
41 0.5 Cr 1 Cr − (1 Cr × 200 ÷ 400)
42 −0.3% (dilutive) Cost = 5% × 20E = E; lost after-tax income = E × 7% × 0.75 = 0.0525E; EPS = (1 − 0.0525) ÷ 0.95 = 0.997. A buyback is accretive only if the earnings yield (5%) exceeds the after-tax yield on the cash used (5.25%)
43 ₹280 (4 × 300 + 200) ÷ 5
44 22.2% σ√(1/n + (1 − 1/n)ρ) = 30% × √(0.1 + 0.45)

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