Someone is asked to take a number from $1$ to $100$. The probability that it is a prime is:
$\dfrac{1}{5}$
$\dfrac{6}{25}$
$\dfrac{1}{4}$
$\dfrac{13}{50}$
Step-by-Step Solution
Key Concept: Number of prime numbers between 1 and 100 is 25. Total outcomes $= 100$.
Stepwise Solution:
Primes between 1 and 100: 25 primes. Total $= 100$. [0.5 Mark]
Probability $= \dfrac{25}{100} = \dfrac{1}{4}$. [0.5 Mark]
Marking Scheme:
• Counting 25 prime numbers: 0.5 Mark
• Calculating probability $= 1/4$: 0.5 Mark
Correct Answer: $\dfrac{1}{4}$