A student asked her professor for a letter of recommendation for a summer program. She estimated that she had a 90 percent chance of getting admitted if she received a strong recommend- dation. She further estimated that the probability that the recommendation would be strong was 0.7. Today she has received a rejection from the summer program and has now concluded that her letter was weak with probability 0.8. In her estimation, what was the probability that a weak letter would lead to a rejection?