Question 1135833
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Answer: <font size=4 color=red>0.24 (choice A)</font>


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Explanation on how to get that answer:


The key phrase here is "if it's observed to be falling", meaning that we know 100% it was observed by people or devices. So we can ignore the "finds" column entirely as we know 100% this rock wasn't just found on the ground without observation first. 


Add up the values in the "falls" column: 0.13+0.04 = 0.17, so this tells us that 17% of the rocks were observed


Of this 17%, we see that 4% are iron since 0.04 is the decimal equivalent to 4%


Divide 0.04 over 0.17 to get
0.04/0.17 = 0.23529411764706


and then round to 2 decimal places
0.23529411764706 becomes <font size=4 color=red>0.24</font> (representing roughly a 24% chance)

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