# Past paper help Watch

1. Hi i really need help on a hardy weinberg question, jan 2011 question 2c, 16% of the population of europe are rhesus negative(rr) and i must find out the population of the rhesus positice(Rr). The mark scheme hasnt helped much at all, id be grateful for any help guys! Xo
2. (Original post by Jessyd)
Hi i really need help on a hardy weinberg question, jan 2011 question 2c, 16% of the population of europe are rhesus negative(rr) and i must find out the population of the rhesus positice(Rr). The mark scheme hasnt helped much at all, id be grateful for any help guys! Xo
rr indicates homozygous recessive.

If you remember the HW equation, this is calculated by q2

Therefore, q2 = 16% = 0.16

You can now solve for q.

We want Rr which indicates heterozygous.
If you remember the HW equation, this is calculated by 2pq.

We have q, but we need p.
This uses the other HW equation: p + q = 1.

Rearranging it shows that p = 1 - q
And now we can solve for p.

Now that we have p and q, we can finally calculate 2pq.
Spoiler:
Show
Solve q = 0.4
∴ Solve p = 0.6
∴ Solve, Rr 2pq = 2 × 0.4 × 0.6 = 0.48
3. Thank you! I actually understand it now

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