Write a scheme function that gives you the average of a list and if the list contains a letter replace it with zero. (Course: Programming languages)

Note: please don't solve it with coding.

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Deline the following functions: a. (pad x ) returns the list x in which each zero element is replaced by the previous non-zero element in the list. Any leading zeros will remain unchanged. b. (aprog x ) returns True if list x is an arithmetic progression and false otherwise first) can be Recall that an arithmetic progression is a sequence in which each element (except the firfserence. obtained from the previous one by adding a fixed value called the common difference difference here is 3 ). (6 marks) Answer: ( debine (pad x ) (cond (mule? x ) (lecx) (sec(cosx)0) (log(ccosx)