# A level maths

Watch
Announcements
#1
Hi,

Does anyone know how to answer the AQA A-level maths stats 2021 assessment resources. More specifically the final question.

Elizabeth's bakery makes brownies. It is known that the mass, X grams, of a brownie may be modelled by normal distribution. 10% of the brownies have a mass of less than 30g. 80% of the brownies have a mass that is greater than 32.5g.
a) Find the mean and standard devisation of X. (7)
b)
i) P(X=/35) (1) --doesn't equal 35
ii) P(X<35) (2)
c) Brownies are baked in batches of 13. Calculate the probability that, in a batch of brownies, no more than 3 brownies are less than 35 grams. YOu may assume that the masses of the brownies are independent of each other (2)
0
1 month ago
#2
(Original post by HollyAJb)
Hi,

Does anyone know how to answer the AQA A-level maths stats 2021 assessment resources. More specifically the final question.

Elizabeth's bakery makes brownies. It is known that the mass, X grams, of a brownie may be modelled by normal distribution. 10% of the brownies have a mass of less than 30g. 80% of the brownies have a mass that is greater than 32.5g.
a) Find the mean and standard devisation of X. (7)
b)
i) P(X=/35) (1) --doesn't equal 35
ii) P(X<35) (2)
c) Brownies are baked in batches of 13. Calculate the probability that, in a batch of brownies, no more than 3 brownies are less than 35 grams. YOu may assume that the masses of the brownies are independent of each other (2)
sure i did it the other day do you want just the answers or how you get them too?
0
1 month ago
#3
(Original post by ImperfectSwift27)
sure i did it the other day do you want just the answers or how you get them too?
Please note the forum guidelines - you should only be posting hints and guidance for those areas where the OP has tried some working and got stuck, NOT posting answers / worked solutions
0
1 month ago
#4
(Original post by HollyAJb)
Hi,

Does anyone know how to answer the AQA A-level maths stats 2021 assessment resources. More specifically the final question.

Elizabeth's bakery makes brownies. It is known that the mass, X grams, of a brownie may be modelled by normal distribution. 10% of the brownies have a mass of less than 30g. 80% of the brownies have a mass that is greater than 32.5g.
a) Find the mean and standard devisation of X. (7)
b)
i) P(X=/35) (1) --doesn't equal 35
ii) P(X<35) (2)
c) Brownies are baked in batches of 13. Calculate the probability that, in a batch of brownies, no more than 3 brownies are less than 35 grams. YOu may assume that the masses of the brownies are independent of each other (2)
For the last part, you need to think about creating a new random variable for the brownie being less than 35 grams with a new distribution. The bit about them being independent is very helpful for this
0
1 month ago
#5
(Original post by davros)
Please note the forum guidelines - you should only be posting hints and guidance for those areas where the OP has tried some working and got stuck, NOT posting answers / worked solutions
Ahh sorry wasn’t aware 😂
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### Do you think receiving Teacher Assessed Grades will impact your future?

I'm worried it will negatively impact me getting into university/college (151)
43.77%
I'm worried that I’m not academically prepared for the next stage in my educational journey (40)
11.59%
I'm worried it will impact my future career (28)
8.12%
I'm worried that my grades will be seen as ‘lesser’ because I didn’t take exams (72)
20.87%
I don’t think that receiving these grades will impact my future (34)
9.86%
I think that receiving these grades will affect me in another way (let us know in the discussion!) (20)
5.8%