Suppose that when the pH of a certain chemical compound is 5.00, the pH measured by a randomly selected beginning chemistry student is a random variable with mean 5.00 and standard deviation .2. A large batch of the compound is subdivided and a sample given to each student in a morning lab and each student in an afternoon lab. Let X = the aver- age pH as determined by the morning students and Y = the average pH as determined by the afternoon students. a. If pH is a normally distributed random variable and there are 25 students in each lab, compute
P(-.1≤ X - Y ≤.1) . (Hint: X - Y is a linear combination of normal variables, so it is normally distributed.
b. If there are 36 students in each lab, but pH deter- minations are not assumed normal, calculate (ap- proximately)
P(-.1≤ X - Y ≤.1).

total amount of money that he should pay if he has not used his duty free exemption is $98

step-by-step explanation:

given a united states citizen returning to the states declares the following items at the customs office: 3 shirts at $8.50 each 2 dresses at $27.50 each 1 pair of gold cuff links at $17.50 per pair. we have to find how much he pay

cost of 3 shirts if one cost at $8.50 is

cost of 2 dresses if one cost at $27.50 is  

cost of 1 pair of gold cuff at $17.50

so, total amount of money that he should pay if he has not used his duty free exemption is   $25.5+$55+$17.50=$98

no solution

step-by-step explanation:

there is not enough information in the problem to solve.

c.

step-by-step explanation:

she should of added 9^2 and 12^2. that is because it is a^2+b^2=c^2. c^2 is the hypotenuse and should always be bigger than the other two numbers. which is why she should of added 9 squared and 12 squared together instead of 15 squared.