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 ▸Solve the simultaneous equation: 3x+2y=8 and 2x+5y=-2
What is the difference between the mode, median and mean?
Factorise and solve the quadratic equation x^2 + 6x + 8 = 0
How do you find the length of a side of a right angled triangle when given the other two side lengths?