MathsCBSE Class 10 · Basic · Board exam 2024, set 430/3/1 · 2 marks · Very short answer

CBSE Class 10 Mathematics Basic 2024: question 25

Set in the CBSE Class 10 board exam of 2024, paper 430/3/1, 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

There are $80$ cards numbered from $1$ to $80$ . One card is drawn at random from them. Find the probability that the number on the selected card is not divisible by $8$ .

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 430/3/1.

Hints

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

Hint 1

First count how many of the numbers 1 to 80 are multiples of 8.

Hint 2

Use $P (not E) = 1 - P (E)$ .

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.

Total outcomes = 80. Numbers divisible by 8 are $8, 16, 24, \dots, 80$ , i.e. 10 numbers. $P (divisible by 8) = \frac{10}{80} = \frac{1}{8}$
1 mark
$P (not divisible by 8) = 1 - \frac{1}{8} = \frac{7}{8}$
1 mark

Answer: $\frac{7}{8}$

Where the marks are

Counts 10 multiples of 8 and finds probability $\frac{1}{8}$ (1 mark)
Uses complement to get $\frac{7}{8}$ (1 mark)

Revise the chapter

Chapter: Probability (notes, formulas, where marks are lost and every past question)
Topic: Probability: Basic Terms and Classical Definition

Practise this chapterBoard-style questions from Probability, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 430/3/1 (Basic): 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.

CBSE Class 10 Mathematics Basic 2024: question 25

Hints

Step-by-step solution

Revise the chapter

More questions from Probability