a level aqa practice paper 3 set 2 help

Hi everyone , have been struggling to complete a couple of statistics question on the paper,could someone help me out please?

Which questions?

the whole of question 19

can you help me please ?

for a i you form two equations using their respective z values and the equation to standardise z values. You solve these simultaneously.
for ii you use the p value of 0.15 given in the question stem to from a binomial distribution with n being 8.
for b you calculate the respective probabilities using the distributions the question has stated, and multiply them together (they threw in a bit of conditional probability chapter in this question)
In further maths, when we combine 2 normal distributions, one of the conditions has to be that they're independent of each other, which is leading me to think that's the answer for part c. However, that is indeed Fmaths and might not apply to a level and the way we combine them is a bit different. That being said, I believe the logic still follows through, therefore, that's the answer I would have put.

I ll do that but is it ok for you to check my work after I have done it?Would really appreciate that.

yhhh sure

hey is it normal that i got a negative standard devviation?

yes you were right but you know for (ll) i got probability equals to 0.
It feels wrong

You know for part b do i have to standirdize the t-N(1.6,0.4) and C-N(6.5,1.4) AND then do normal distribution or plug the values in the calculator straight away?

n is the number of trials in Binomial right? So why would you test for the probability of getting more than 65 then the total number of trials is 8? You get 0 because there is no chance that he sells more than 65 litres on 65 out of 8 days. The question says at least 3 days so the probability you should be calculating is P(X>=3)

I would plug them in straight away. I'm not sure how you could get the necessary values by standardising. Wouldnt that take you round in a circle?

Looks right