Answer:
b
Step-by-step explanation:
because we can not some times change the places in addition so b is the correct answer
Multiply the first equation by -2. It turns into 4x+18y=50 and the other one stays -4x-9y=-23. Then you "eliminate" the equations by "adding" them. Set it up like this:
4x+18y=50
+
-4x-9y=-23
4x-4x= 0. 18y-9y= 9y and 50-23= 27
SO: 9y= 27 and y= 3
And then you plug that in to one equation: 4x +18(3)= 50. 4x= 50-(18*3)
4x= -4, so x=-1.
Plug it back in to check!
Hope this helps. Happy solving! :)
Answer:
b. 2.28%.
Step-by-step explanation:
Mean temperatue (μ) = 1000°F
Standard Deviation (σ) = 50
°F
For any temperature value, X, the z-score is given by:
For X= 900°F

A z-score of -2.0 corresponds to the 2.28-th percentile of a normal distribution. Therefore, the probability that X<900 is:
