GATE AG 2018 • Q41 NAT • 2 Marks

Section 1: Engineering Mathematics

Probability and Statistics

Subtopic: Mean, median, mode and standard deviation

Question Statement:

In a box, there are 2 red, 3 black and 4 blue coloured balls. The probability of drawing 2 blue balls in sequence without replacing, and then drawing 1 black ball from this box is _________ %.

Official Answer Key:

6.80 to 7.20

Step-by-Step Solution & Explanation

Total balls = 2 + 3 + 4 = 9. P(1st blue) = 4/9; P(2nd blue | 1st blue) = 3/8; P(black on 3rd draw) = 3/7. P = (4/9)(3/8)(3/7) = 36/504 = 0.07143 = 7.14 % — within the official range 6.80–7.20. Section 2 — Farm Machinery 6 questions · 9 marks

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