Answer:
-1
Step-by-step explanation:
Given: Mean= 25 minutes.
Standard deviation= 2 minutes
x= 23 minutes.
Lets find the z-score for the number of sandwiches delivered in less than 23 mins.
Formula: Z-score= 
Z-score= 
⇒ Z-score= 
∴ Z-score will be -1
Hence, -1 is the z-score for the number of sandwiches delivered in less than 23 minutes.
Ok so this is conic sectuion
first group x's with x's and y's with y's
then complete the squra with x's and y's
2x^2-8x+2y^2+10y+2=0
2(x^2-4x)+2(y^2+5y)+2=0
take 1/2 of linear coeficient and square
-4/2=-2, (-2)^2=4
5/2=2.5, 2.5^2=6.25
add that and negative inside
2(x^2-4x+4-4)+2(y^2+5y+6.25-6.25)+2=0
factor perfect squares
2((x-2)^2-4)+2((y+2.5)^2-6.25)+2=0
distribute
2(x-2)^2-8+2(y+2.5)^2-12.5+2=0
2(x-2)^2+2(y+2.5)^2-18.5=0
add 18.5 both sides
2(x-2)^2+2(y+2.5)^2=18.5
divide both sides by 2
(x-2)^2+(y+2.5)^2=9.25
that is a circle center (2,-2.5) with radius √9.25
P(B) = 0.75.
For independent events, P(A and B) = P(A)*P(B). This gives us
1/8 = 1/6(x)
Divide both sides by 1/6:
1/8 ÷ 1/6 = x
1/8 × 6/1 = x
6/8 = x
3/4 = x
0.75 = x
