BMAT 2019 Question 26

BMAT2019Q26.pdf (43,8,KB)

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Hey Dorsa, I’m sorry for the delay and thanks for the feedack!
I also marked D, but I dot know why the answer is E.

Hi! i found this explanation online:

probability having two ¹⁰B with mass of 26 = 0,2 * 0,2 = 0,04

probability of 1 ¹⁰B and 1 ¹¹B with mass of 27 = (O,2 * O,8) + (0,2 * 0,8) = 0,32
if you draw a probability tree diagram you see you could have two possibilities ¹⁰B ¹¹B or ¹¹B ¹⁰B

probability having two ¹¹B with mass of 28 = 0,8 * 0,8 = 0,64

so a ratio of 1:8:16

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