Question 10:
(a) It is found that 60% of the students from a certain class obtained grade A in English in O level trial examination.
If 10 students from the class are selected at random, find the probability that
(i) exactly 7 students obtained grade A.
(ii) not more than 7 students obtained grade A.
(b) Diagram below shows a standard normal distribution graph representing the volume of soy sauce in bottles produced by a factory.
It is given the mean is 950 cm3 and the variance is 256 cm6. If the percentage of the volume more than V is 30.5%, find
(i) the value of V,
(ii) the probability that the volume between 930 cm3 and 960 cm3.
Solution:
(a) It is found that 60% of the students from a certain class obtained grade A in English in O level trial examination.
If 10 students from the class are selected at random, find the probability that
(i) exactly 7 students obtained grade A.
(ii) not more than 7 students obtained grade A.
(b) Diagram below shows a standard normal distribution graph representing the volume of soy sauce in bottles produced by a factory.
![](http://spmaddmaths.blog.onlinetuition.com.my/wp-content/uploads/sites/3/2018/08/Picture24.png)
(i) the value of V,
(ii) the probability that the volume between 930 cm3 and 960 cm3.
Solution: