Question
Seven balls out of which 4 are red and the rest are green
are to be arranged in a row. Find the number of arrangements in which all four red balls are not placed together.Solution
Total number of ways of arrangement = 7! = 5040 ways
If we consider 4 red balls as one item, number of arrangements among themselves = 4! = 24 ways
Number of arrangements of remaining 4 items = 4! = 24 ways
Therefore, required number of ways = 5040 – (24 × 24) = 4464 ways
20, 95, 220, 275, 620, 895
In each of the following number series, one term is wrong. Find the wrong term.
4, 7, 12, 21, 28, 39, 52
- Find the wrong number in the given number series.
10, 26, 58, 106, 170, 258 Find the wrong number in given number series.
2658, 2654, 2681, 2645, 2999, 2918
- In the given number series, find the wrong number.
4, 9, 19, 39, 79, 159, 319 In each of the following, one term is wrong. Find the WRONG term.
2, 6, 18, 54, 108, 486
Find the wrong number in the given number series.
76, 81, 96, 123, 156, 201Find the wrong number in the given number series.
7, 15, 31, 57, 87, 127
132, 136, 109, 125, 2, 36
48, 72, 104, 144, 192, 251
