Question
Among a set of 6 black balls and 3 white balls, how many
selections of 5 balls can be made such that at least 3 of them are black balls?Solution
Selecting at least 3 black balls from a set of 6 black balls in total selection of 5 balls can be 3 black and 2 white balls 4 black and 1 white balls 5 black and 0 white balls Therefore, our solution expression looks 6C3 × 3C2 + 6C4 × 3C1 + 6C5 × 3C0 = 20 × 3 + 15 × 3 + 6 × 1 = 60 + 45 + 6 = 111 ways
5, 15, 30, 135, 405, 1215, 3645
Select the wrong term in the series.
7, 14, 42, 210, 1470, 17640
In the following question, select the wrong number from the given alternatives.
43, 50, 64, 85, 113, 138
Arrange the following words in a logical and meaningful order.
1. Monkey
2. Elephant
3. Rat
4. Fly
5. Lion
In the following question, select the wrong number from the given alternatives.
48, 50, 52, 57, 59, 68, 75
Find the wrong number in the series given below.
6, 19, 59, 182, 544, 1637
Find the wrong number in the series given below.
3, 10, 89, 99, 301, 908
In this question, one term in the number series is wrong. Find out the wrong term.
130, 135, 143, 154, 168, 183, 205
Find the wrong number in the given series.
5, 3, 6, 17.25, 64.75
Find out the Wrong number in the following number series.
2, 123, 204, 256, 278, 287