Can someone confirm my answer please (S1)

The bottling process can be adjusted so that the mean changes but the variance is unchanged (the variance is 3.2, so the standard deviation is the root of this)
What should the mean be changed to in order to have only a 0.1% chance of a bottle having less than 700 ml of sparkling water? Give your answer correct to 1 decimal place.

I worked this out and got 699.5 as my final answer for the new mean.
However, I think the mark scheme is dodgy because
(a) It got a different answer to me
(b) It uses 0.01 as the probability first even though the question clearly states it is 0.1.
(c) It then goes on to use 0.001 as the probability. So two incorrect probabilities used!
Can someone work this out please and see if you get the same answer as me?
This question comes from question 7 part (d) of the Edexcel S1 Solomon B paper.

Reply 1

Zacken

22

Original post by Jessika300599

The bottling process can be adjusted so that the mean changes but the variance is unchanged (the variance is 3.2, so the standard deviation is the root of this)
What should the mean be changed to in order to have only a 0.1% chance of a bottle having less than 700 ml of sparkling water? Give your answer correct to 1 decimal place.

I worked this out and got 699.5 as my final answer for the new mean.
However, I think the mark scheme is dodgy because
(a) It got a different answer to me
(b) It uses 0.01 as the probability first even though the question clearly states it is 0.1.
(c) It then goes on to use 0.001 as the probability. So two incorrect probabilities used!
Can someone work this out please and see if you get the same answer as me?
This question comes from question 7 part (d) of the Edexcel S1 Solomon B paper.