R would be iv because you have to do cross multiplication.
ec would be 3 because you have to do cross multiplication.
Which problem do u need help with I can help u with all. All of them are scientific notation so it's easy and I will tell u an easy way to solve it
A) The mean would be 1.842 and the standard deviation would be 1.339.
b) It would not be unusually low.
Explanationa) This can be modeled as a binomial distribution, since there are two outcomes (7 or not 7), the events are independent (getting a 7 on one spin does not influence the chance of a 7 on the next spin) and there are a fixed number of trials (70). In a binomial distribution, the mean is given by n*p, where n is the number of trials and p is the probability.
μ=n*p=70*(1/38) = 1.842.
The standard deviation of a binomial distribution is given by
σ=√(n*p*(1-p))=√(70(1/38)(37/38)=1.339.
b) To determine if this is unusually low, we find the probability:

Since this is not below 0.05, we do not consider this unusual.
950 times 3/4 or 0.75 = 712.5. 712.5 times 1/3 or 0.33 = 237.49 so that is the answer $237.49. Hope I helped please put Brainiest!