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Maths help.

Can you help me with this question please.

Bethany flips a biased coin twice.
The probability that the coin will land on tails both times is 0.16.
Calculate the probability the coin will land on heads both times. (It's 3 marks)
(I tried doing a tree diagram but got like 3 different answers. 🤔) Thank you.
Original post by Maths1210
Can you help me with this question please.

Bethany flips a biased coin twice.
The probability that the coin will land on tails both times is 0.16.
Calculate the probability the coin will land on heads both times. (It's 3 marks)
(I tried doing a tree diagram but got like 3 different answers. 🤔) Thank you.


If it lands on tails with probability pp then it lands on heads with 1p1-p. Draw a probability tree with these for each flip.

You'd find that for two tails on two flips, you must have probability p2p^2
Reply 2
0.36
Reply 3
Original post by RDKGames
If it lands on tails with probability pp then it lands on heads with 1p1-p. Draw a probability tree with these for each flip.

You'd find that for two tails on two flips, you must have probability p2p^2



So to start off would the probability for tails be 0.4 and tails again 0.4 as it's the square foot of 16?
Reply 4
Original post by Maths1210
So to start off would the probability for tails be 0.4 and tails again 0.4 as it's the square root of 0.16?


Then would heads be 0.96 for both branches. I don't know where to go from here though.
Original post by Maths1210
So to start off would the probability for tails be 0.4 and tails again 0.4 as it's the square foot of 16?


The probability for tails is 0.4, yes. This comes from the fact that p2=0.16p^2=0.16 so p=0.4p=0.4

Hence, what must the probability for a single heads be...?
Reply 6
Original post by RDKGames
The probability for tails is 0.4, yes. This comes from the fact that p2=0.16p^2=0.16 so p=0.4p=0.4

Hence, what must the probability for a single heads be...?


Would two heads be one head squared and one head be 0.96? As 1-0.96= 0.4?
Reply 7
Original post by Maths1210
Would two heads be one head squared and one head be 0.96? As 1-0.96= 0.4?


Oh wait would it be 0.6?
Original post by Maths1210
Would two heads be one head squared and one head be 0.96? As 1-0.96= 0.4?


What? No... I'm not sure where you're pulling this 0.96 from?

Probability of tails is 0.4, so probability to get a head on a toss is 1-0.4 which is.....?
Reply 9
Original post by RDKGames
What? No... I'm not sure where you're pulling this 0.96 from?

Probability of tails is 0.4, so probability to get a head on a toss is 1-0.4 which is.....?


Oh I thought it was 0.04 so would it be 0.6?
Original post by Maths1210
Oh I thought it was 0.04 so would it be 0.6?


Yes that's the probability to get heads on a toss.
Reply 11
Original post by RDKGames
Yes that's the probability to get heads on a toss.


So 2 heads = 0.6 × 0.6 = 0.36?
Original post by Maths1210
So 2 heads = 0.6 × 0.6 = 0.36?

yes
Reply 13
Original post by RDKGames
yes


Thank you so much. I totally overcomplicated this question. 😂

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