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How to calculate conditional probabilities? E.g, say we roll a fair standard six sided die, what is the probability we rolled a 2, given that the roll is even?

Brief overiew of the answer: Since the roll is even, we either rolled a 2, a 4 or a 6, all with equal probabilities. Therefore, the probability we rolled a 2 is equal to 1/3.Formal answer: We write P(2|E) to...
KB
Answered by Karlo B. • Maths tutor
6275 Views

(x(x+1))/2 = 3 Solve For x.

Multiply both sides by 2 ( (x(x + 1) ) = 6 ) Multiply out the brackets ( x 2 + x = 6 ) Bring the 6 across ( x 2 + x - 6 = 0 ) Either using the quadratic formula or spotting the factors solve for x ( x = -3 o...
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Answered by Robert T. • Maths tutor
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A bag has 3 red balls and 5 green balls. I take out 2 balls, without replacing them. What is the probability of choosing at least one red ball? Give your answer to 3 decimal places.

Student would likely draw a tree diagram to represent the different outcomes. They should recognise that you must add the probability of choosing only one red ball, and two red balls. The outcomes are:Green ...
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Answered by Joe G. • Maths tutor
10962 Views

There are two points 'A' and 'B' on a graph, their coordinates are (0,1) and (10,6) respectively. 1)Find the equation of the line that runs through both of these points.2)Find the equation of a line perpendicular to this through point 'B'.

Draw a graph to see the question more clearly.1) Find the slope using the rise over run formula. ( m = 1/2 ) Put this slope into the equation of a line formula along with one of the points. ( y = (1/2)*x + 1...
RT
Answered by Robert T. • Maths tutor
2854 Views

Factorise and solve x^2 -8x=15=0

x=3 or x=5
VA
Answered by Vineet A. • Maths tutor
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