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In a bag of 25 coloured balls, 7 are orange, 6 are yellow and the rest are green. Laura picks out a ball and records its colour but doesn't return it to the bag, she then repeats this twice more. What is the probability of Laura getting 3 yellow balls?

Answer: 1/115 The easiest way to solve this problem is to draw part of a tree diagram to see the probabilites of each colour being picked each time Laura pulls a ball out of the bag (a full diagram isn't nee...
MS
Answered by Manon S. • Maths tutor
3638 Views

How do I rationalised and simplify surds?

Say I have a fraction with 2 surds, such as √10 / √6. To rationalise this, we need to get the dominator (bottom fraction) to be an integer. As √10 / √6 x 1 still gives √10 / √6, and we can write 1 as √6 / √6...
TG
Answered by Tabitha G. • Maths tutor
4960 Views

Ian earns £420 a week after a 5% rise. What was his pay before?

Ian had a 5% rise, so £420 = 105% of his original pay To find 1% of his original earnings, divide £420 by 105. Multiply this by 100 to find his old pay: 1% of his original earnings = 420/105 = £4 Original ea...
HS
Answered by Haris S. • Maths tutor
7960 Views

Solve x^2+2x-4, leaving your answer in the simplist surd form. (4marks)

Simplist surd form means use Quadratic equation Write out Quadratic equation Write out value of a, b and c Fit these values into equation Now the maths starts. Area's where students are likely to make mistak...
DR
Answered by Desnie R. • Maths tutor
3635 Views

Why is n^0 always 1 and not 0?

Anything raised to the zeroth power is a difficult thing to get your head around. The easiest explanation (not a full proof) is to look at what happens as we go down in powers of n: n^3=n n n n^2=(n^3)/n=n n...
JC
Answered by Joseph C. • Maths tutor
5088 Views