Answer:
456
Step-by-step explanation:
Let X be the SATscore scored by the students
Given that X is normal (1000,200)
By converting into standard normal variate we can say that
is N(0,1)
To find the top 10% we consider the 90th percentile for z score
Z 90th percentile = 1.28

i.e. only students who scored 456 or above only should be considered.
Base number, like in the equation 4², 4 is the base number
First you need to multiple 7X0.02 and then add that number to 7
Distribute first
a(b+c)=ab+ac
7y(8y-7)=56y^2-49y
now we have
56y^2-49y+46y
56y^2-3y
tada