In a box there are 20 balls.7 of the balls are white. The first ball drawn from the box is white. What is the probability that the second ball will be white
wouldn't there now be 6 white balls left out of the remaining 19 ?
so ....
To find the probability that the second ball will be white, we need to consider the number of white balls and the total number of balls remaining in the box.
Given:
Total number of balls = 20
Number of white balls = 7
Since the first ball drawn was white, there are now 19 balls remaining in the box, including 6 white balls.
The probability of drawing a white ball on the second draw is the number of favorable outcomes (drawing a white ball) divided by the total number of possible outcomes (drawing any ball).
The probability of drawing a white ball on the second draw is:
Number of white balls remaining / Total number of balls remaining
Number of white balls remaining = 6
Total number of balls remaining = 19
Therefore, the probability of drawing a white ball on the second draw is 6/19 or approximately 0.3158 (rounded to four decimal places).
To calculate the probability of drawing a white ball on the second draw, we need to consider two scenarios:
1. The first white ball is not put back in the box after being drawn.
2. The first white ball is put back in the box after being drawn.
Let's analyze each scenario separately:
1. The first white ball is not put back in the box:
In this case, after the first white ball is drawn, there will be 19 balls left in the box, and 6 white balls remaining. Therefore, the probability of drawing a white ball on the second draw is given by:
Probability = (Number of white balls after the first draw) / (Total number of balls after the first draw)
Probability = 6 / 19
2. The first white ball is put back in the box:
In this scenario, after drawing the first white ball, it is returned to the box. So, there will still be 7 white balls and 20 balls in total. Consequently, the probability of drawing a white ball on the second draw is:
Probability = (Number of white balls) / (Total number of balls)
Probability = 7 / 20
Therefore, depending on whether the first ball is replaced or not, the probability of drawing a white ball on the second draw can be calculated as either 6/19 or 7/20.