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A bag contains 25 balls. Some… (Class 10 Maths 2026, Q25)

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MathsCBSE Class 10 · Standard · Board exam 2026, set 30/5/1 · 2 marks · Very short answer

CBSE Class 10 Mathematics Standard 2026: question 25

Set in the CBSE Class 10 board exam of 2026, paper 30/5/1, section B, question 25, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q25 · 2 marks · Very short answerProbability

A bag contains 25 balls. Some of them are yellow and others are green. One ball is drawn at random. If probability of getting a green ball is , then find the number of yellow balls.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 30/5/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

The two events 'yellow' and 'green' are complementary.

Hint 2

Find P(yellow) first.

Hint 3

P(yellow) = number of yellow balls ÷ total balls.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. Each ball is either yellow or green, so , i.e. .

    1 mark

  2. Number of yellow balls .

    1 mark

Answer: 10 yellow balls

Where the marks are

  • Uses (1 mark)
  • Number of yellow balls = 10 (1 mark)

Revise the chapter

  • Chapter: Probability (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Probability, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 30/5/1 (Standard): every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.