Question
A bag contains 30 white and some black balls. If the
probability of drawing a black ball from the bag is 1.4 times that of drawing a white ball, find the number of black balls in the bag.Solution
 Given, Number of white balls = 30 Let x be the number of black balls. Total number of balls in the bag = 30 + x Also, the probability of drawing a black ball from the bag is 1.4 times that of drawing a white ball. ⇒ x/ (30 + x) = 1.4[30/ (30 + x)] =5x = 7×30 ⇒ x = 42 Hence, the number of black balls in the bag = 42.
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∆ABC and ∆DEF are similar and their areas are respectively 16 cm2 and 64 cm 2 . If EF = 6 cm BC is?
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