There are n sweets in a bag. 6 of the sweets are orange. The rest of the sweets are yellow. Hannah takes a sweet from the bag and eats it. Hannah then takes at another sweet. The probability that Hannah eats two orange sweets is 1/3. Show that n²-n-90=0
P(2 orange sweets) = P(orange sweet) * P(orange sweet)
(6/n) * (5/(n-1)) = 1/3
30/(n(n-1)) = 1/3
90 = n(n-1)
90 = n2-n
n2-n-90=0 as required
TV
Related Maths GCSE answers
All answers ▸Factorise: x^2+2x-3
How do you solve the simultaneous equations 3x + 4y = 5 and 2x – 3y = 9
A ball, dropped vertically, falls d metres in t seconds. d is proportional to the square of t. The ball drops 45 metres in the first 3 seconds. How far does the ball drop in the next 7 seconds?
A rectangle has a total perimeter of 32cm with sides of length '3x' and 'x+8'. Solve for x.