Answer:
The number of wrapping paper sold was 32 and the number of magazines sold was 40
Step-by-step explanation:
Let
x ----> the number of wrapping paper sold
y ----> the number of magazines sold
we know that
The classes sold 72 items
so
----> equation A
The classes earned $222 for their school
so
----> equation B
Solve the system of equations by graphing
Remember that the solution of the system of equations is the intersection point both graphs
using a graphing tool
The solution is (32,40)
see the attached figure
therefore
The number of wrapping paper sold was 32 and the number of magazines sold was 40
Is means equals. The number before the words Less than means that number is subtracted from that number. 3 times a number, we don’t know the number so we use a variable, 3x. So..........
3x-5=10
This question is incomplete, the complete question is;
X and Y are independent Gaussian (Normal) random Variables. X has mean 13.9 and variance 5.2; Y has mean 6.9 and variance 3.8. . (a) Calculate P( W> 10)
Answer:
P( W> 10) is 0.1587
Step-by-step explanation:
Given that;
X ⇒ N( 13.9, 5.2 )
Y ⇒ N( 6.9, 3.8 )
W = X - Y
Therefore
E(W) = E(X) - E(Y)
= 13.9 - 6.9 = 7
Var(W) = Var(X) + Var(Y) -2COV(X.Y)
[ COV(X,Y) = 0 because they are independent]
Var(W) = 5.2 + 3.8 + 0
= 9
Therefore
W ⇒ N( 7, 9 )
so
P( W > 10 )
= 1 - P( W ≤ 10 )
= 1 - P( W-7 /3 ≤ 10-7 /3 )
= 1 - P( Z ≤ 1 ) [ Z = W-7 / 3 ⇒ N(0, 1) ]
from Standard normal distribution table, P( Z ≤ 1 ) = 0.8413
so
1 - P( Z ≤ 1 ) = 1 - 0.8413 = 0.1587
Therefore P( W> 10) is 0.1587
