The recursive definition given below defines a set S of strings over the alphabet {a, b}: Base case: λ ∈ S and a ∈ S Recursive rule: if x ∈ S then, xb ∈ S (Rule 1) xba ∈ S (Rule 2) This problem asks you to prove that the set S is exactly the set of strings over {a, b} which do not contain two or more consecutive a's. In other words, you will prove that x ∈ S if and only if x does not contain two consecutive a's. The two directions of the "if and only if" are proven separately. (a) Use structural induction to prove that if a string x ∈ S, then x does not have two or more consecutive a's.

Need this at the city museum, child admission is 6 and adult admission is 9.20. on tuesday, 132 tickets were sold for a total sales of 961.60. how many adult tickets were sold that day?

There are two major tests of readiness for college: the act and the sat. act scores are reported on a scale from 1 to 36. the distribution of act scores in recent years has been roughly normal with mean µ = 20.9 and standard deviation s = 4.8. sat scores are reported on a scale from 400 to 1600. sat scores have been roughly normal with mean µ = 1026 and standard deviation s = 209. reports on a student's act or sat usually give the percentile as well as the actual score. the percentile is just the cumulative proportion stated as a percent: the percent of all scores that were lower than this one. tanya scores 1260 on the sat. what is her percentile (± 1)?

Eric and shiloh each have a savings account. the ratio of eric’s account balance to shiloh’s account balance is 4: 3. together they have a total of $140 in their accounts. use the tape diagram below to you determine the balance of eric’s account.