Question:
A box contains 90 discs which are numbered from 1 to 90. If one disc is drawn at random from the box, the probability that it bears a perfect square number is:
A box contains 90 discs which are numbered from 1 to 90. If one disc is drawn at random from the box, the probability that it bears a perfect square number is:
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To find probability of a perfect square, count how many square numbers exist in the given range and divide by total number of elements.
Updated On: Aug 11, 2025
- 1/10
- 1/11
- 1/90
- 1/9
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The Correct Option is A
Solution and Explanation
Step 1: List perfect squares between 1 and 90
\[ 1^2 = 1,\quad 2^2 = 4,\quad 3^2 = 9,\quad 4^2 = 16,\quad 5^2 = 25,\quad 6^2 = 36,
7^2 = 49,\quad 8^2 = 64,\quad 9^2 = 81 \] Total = 9 perfect squares Step 2: Total number of discs = 90
So, probability: \[ P = \frac{9}{90} = \frac{1}{10} \] % Final Answer \[ \boxed{\frac{1}{10}} \]
\[ 1^2 = 1,\quad 2^2 = 4,\quad 3^2 = 9,\quad 4^2 = 16,\quad 5^2 = 25,\quad 6^2 = 36,
7^2 = 49,\quad 8^2 = 64,\quad 9^2 = 81 \] Total = 9 perfect squares Step 2: Total number of discs = 90
So, probability: \[ P = \frac{9}{90} = \frac{1}{10} \] % Final Answer \[ \boxed{\frac{1}{10}} \]
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