2026-09-10T00:15:20.300665 image/svg+xml Matplotlib v3.10.9, https://matplotlib.org/ © EAGLE BEACON GLOBAL Calculate the probability that a marble taken at ...
Question 1 Report
Calculate the probability that a marble taken at random from a jar is green. The tree diagram shows the three colours in the jar, which holds red, green and yellow marbles only. The probability of red is \(\frac{1}{4}\) and the probability of yellow is \(\frac{2}{5}\). Give your answer as a fraction.
Answer Details
The probabilities of all possible colours must add to 1. First add the probabilities for red and yellow using a common denominator:
\[\frac{1}{4}+\frac{2}{5}=\frac{5}{20}+\frac{8}{20}=\frac{13}{20}.\]
Green is the remaining probability:
\[P(\text{green})=1-\frac{13}{20}=\frac{7}{20}.\]
The required probability is \(\frac{7}{20}\). [3 marks]
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