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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
6261 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...
RT
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 ...
JG
Answered by Joe G. • Maths tutor
10951 Views

Describe the trend in reactivity down group 1 of the periodic table.

Down group 1 the elements are more reactive. This because the size of the atom gets larger and the outermost electron feels less attraction to the nucleus.
LD
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A car is travelling at 10m/s. It then accelerates at a constant rate.Find the time taken for the car to travel 1km if the car’s final velocity is then 22m/s .

s=((u+v)/2)t1000=((10+22)/2)t1000=(16)tt= 62.5s
MW
Answered by Mark W. • Physics tutor
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