Easy MCQ +4 / -1 PYQ · JEE Mains 2024

Two marbles are drawn in succession from a box containing 10 red, 30 white, 20 blue and 15 orange marbles, with replacement being made after each drawing. Then the probability, that first drawn marble is red and second drawn marble is white, is

  1. A $\frac{4}{25}$
  2. B $\frac{2}{3}$
  3. C $\frac{2}{25}$
  4. D $\frac{4}{75}$ Correct answer

Solution

<p>To solve this problem, we need to calculate the probability of two independent events occurring in succession: the first marble drawn is red, and the second marble drawn is white. Since the drawing is with replacement, the number of marbles of each color remains the same for both draws.</p> <p>The total number of marbles in the box is the sum of red, white, blue, and orange marbles:</p> $$ \text{Total marbles} = 10 (\text{red}) + 30 (\text{white}) + 20 (\text{blue}) + 15 (\text{orange}) = 75. $$ <p>The probability of drawing a red marble in the first draw is the number of red marbles divided by the total number of marbles:</p> $P(\text{First is red}) = \frac{10}{75}.$ <p>Since the marble is replaced, the probability of drawing a white marble in the second draw remains as the number of white marbles divided by the total number of marbles:</p> $P(\text{Second is white}) = \frac{30}{75}.$ <p>The probability of both independent events occurring in succession (drawing a red marble first and then a white marble) is the product of their individual probabilities:</p> $$ P(\text{First is red and second is white}) = P(\text{First is red}) \times P(\text{Second is white}) = \frac{10}{75} \times \frac{30}{75}. $$ <p>Now, let's calculate this probability:</p> <p>$$ P(\text{First is red and second is white}) = \frac{10 \times 30}{75 \times 75} = \frac{300}{5625}= \frac{4}{75}. $$</p> <p>Therefore, the correct answer is</p> Option D $\frac{4}{75}.$

About this question

Subject: Mathematics · Chapter: Probability · Topic: Classical and Axiomatic Probability

This question is part of PrepWiser's free JEE Main question bank. 143 more solved questions on Probability are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →