Question
In a class, the ratio of number of boys to number of
girls is 6:5. If 1 boy joined the class and 5 girls left the class, then the ratio becomes 7:5. Find the actual number of girls in the class.Solution
Let initially the number of boys and girls be 6x and 5x, respectively.
(6x + 1) : (5x − 5) = 7 : 5
Or, 5(6x + 1) = 7(5x − 5)
Or, 30x + 5 = 35x − 35
Or, 5x = 40 ⇒ x = 8
Therefore, number of girls = 5 × 8 = 40Â
Find the wrong number in the given number series.
120, 126, 138, 162, 220, 306
217Â Â Â Â 210Â Â Â Â Â 236Â Â Â Â Â 299Â Â Â Â Â 423Â Â Â Â 640
...112, 222, 440, 872, 1717 , 3424
In each of the following giving number series, a wrong number is given. Find out the wrong number?
82, 81, 86, 110, 168, 287
- 78, 86, 71, 95, 60, 112
2100, 2140, 2186, 2240, 2300, 2372
9, 10, 12, 18, 42, 160
A-5,  A,  35,  52, 78, 115
Find the wrong number in the given number series.
233, 206, 183, 152, 125, 98
Find the wrong number in the given number series.
2, 4, 12, 48, 120, 1440
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