One Child Policy Riddle Contest

Here’s a riddle about the one-child policy in China. The person who posts the right answer first as a comment gets a prize. There may also be runner-up prizes for other correct answers.

1. China has a one-child policy. Traditionally, boys have been favored over girls because girls often leave the family when they marry, whereas boys tend to support their aging parents. However, abortion for this purpose is illegal. Assuming everyone has only one child, how will the distribution of boys vs. girls be in the next generation. (Hint: try using probability of getting a boy = 0.50, then try again using a number smaller than 0.5)
2. In actuality, rural families, if they do not have a boy for their first child, may try for a second child. Urban families can only have one child, however, no matter the gender. How will component of the rule affect the proportion of boys to girls?
3. One more caveat: families may choose to have a second child, but they must pay an additional tax. How do you think this will affect the gender distribution, in comparison to other countries?


6 thoughts on “One Child Policy Riddle Contest

  1. The question is, WHEN are you coming back? By the time you come back, our dog may have grown old and died of natural causes. I’m losing hope my friend, losing hope. I miss you.

  2. This is a riddle that must necessarily have more than one acceptable answer. The reality is that more boys are born than girls, and that people violate the abortion law. What is in fact happening is that the gender ratio is becoming skewed in favor of males in China (so what have I won?)

  3. Here is the answer: mathematically there is no change. If the chances of having a boy are 50% then having a one child policy where you may have another child if the first one is a boy does not change the equation. At every step there is a 50% chance of having a boy or a girl.

  4. Or, if the percentage of girls is 40% and boys 60%, it still stays the same, girls 40% and boys 60%. Hint: Draw some probability tree diagrams.

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