Binomial Probability Distribution Problem. Also hey - I just joined the forum!

Hello.
I am a beginner, but I really want to get my head around mathematics.

I am doing an online course at the moment on, and I have just moved onto binomial distributions.
I want to know everything I can about calculating them really.

But I am stuck I have added a picture of my workings out of Q4, where am I going wrong?

We are given the answers to the problems, but I cannot figure out how to come to the answers.
Here is the case study and questions that I cannot get my head around.

Case Study
'Amir buys a chocolate bar everyday during a promotion that says one out of six chocolate bars has a gift coupon within.

Q4. Amir buys a bar everyday for six weeks. What is the probability that he gets at least three gift coupons?

Q5. How many days of purchase are required so that Amirs chance of getting at least one gift coupon is .95 or greater.

I cannot figure out how question 4. comes to 0.07 or how Question 5. comes to 17 days based upon the information the course equips us with before the questions are presented.

Id really appreciate some help as I'd love to be able to tackle these questions, independently. If you could break down the steps as simply as possible that would be ideal and I will not be offended!

Thanks in advance.
Rosie Lavis, MSc, Bsc. x

Regarding question 4, my guess is that the person setting the answers for this particular online course made a typo. All of your work looks good to me, and time I try the problem, the answer comes out to 0.97, just like you get. Is this perhaps someone you can contact to ask about this issue?

As for question 5, think about it step by step. Because you're interested in Amir getting at least 1 prize, that means you can just calculate the probability of Amir not getting any prizes and subtract that result from 1. So, then it's just a matter of noting the number of days it takes for the probability of Amir not winning to be less than 0.05.