Skip to content

How many positive three… (Class 10 Maths SQP 2024-25, Q22B)

questionbuddy.in/q/cbse-10-maths-2024-25-sqp-standard-q22b-how-many-positive-digit-integers

MathsCBSE Class 10 · Standard · Sample paper, session 2024-25 · 2 marks · Very short answer

CBSE Class 10 Mathematics Standard sample paper 2024-25: question 22(B)

From the official CBSE sample question paper for 2024-25, section B, question 22(B), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q22(B) · 2 marks · Very short answerProbability

How many positive three digit integers have the hundredths digit and unit's digit ? Find the probability of selecting one such number out of all three digit numbers.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2024-25.

Hints

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

Hint 1

How many three-digit numbers are there in all?

Hint 2

If the first and last digits are fixed, how many choices are left for the middle digit?

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. Three-digit numbers run from 100 to 999, so there are of them.

    ½ mark

  2. Numbers with hundreds digit 8 and units digit 5 are . Only the tens digit can vary ( to ), so there are such numbers.

    1 mark

  3. ½ mark

Answer: 10 such numbers; probability

Where the marks are

  • Total three-digit numbers = 900 (½ mark)
  • Identifies the 10 numbers 805 to 895 (1 mark)
  • Probability (½ 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 paperSample paper 2024-25 (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.