Question
Factorise: $(l + m)^2– (l – m)^2$
✓
Answer
$(l + m)^2– (l – m)^2$
$= l{(l + m) – (l – m)} {(l + m) + (l – m)} . . . .$ [Applying Identity $III$
$= (2m) (2l)$
$= 4lm$
$= l{(l + m) – (l – m)} {(l + m) + (l – m)} . . . .$ [Applying Identity $III$
$= (2m) (2l)$
$= 4lm$
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Marble Game
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Jyoti :
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Pramod is babysitting his little sister Monika and her two friends, Puja and Jyoti. Monika is wearing red, Puja is wearing blue and Jyoti is wearing green coloured clothes.
Pramod fills a bucket with 12 red (R) marbles. 8 blue (B) marbles and 4 green (G) marbles. He tells the giris that they will play a game. He will reach into the bucket and pull out a marble at random. The girl whose clothes match the colour of the marble scores 1 point.
(i) What is the probability of each girl scoring 1 point on the first draw?
Monika:
Puja:
Jyoti :
(ii) What is the probability of not drawing a green marble on the first draw?
(iii) If two marbles of each colour are added to the bucket, do the probabilities in part (a) change? Explain your answer.
(iv) If the number of each colour is doubled, do the probabilities in part (a) change? Explain why or why not.
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