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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...

Answered by Manon S. • Maths tutor

3308 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 /...

Answered by Tabitha G. • Maths tutor

4601 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 =...

Answered by Haris S. • Maths tutor

7558 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
DR
Answered by Desnie R. • Maths tutor
3334 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=nnn ...

Answered by Joseph C. • Maths tutor

4593 Views