13) Solve the system of equations by elimination.
2x-y =7
x + 3y = 0

x and y are 3 and -1 respectively

Step-by-step explanation:

let me help you with substitutuion method if it will help

let

2x - y = 7equation 1

x + 3y =0 equation2

from equation 2

x + 3y =0 equation2

x = -3yequation3

substitute for x  = -3 in equation 1

2x - y = 7equation 1

2(-3y) -y = 7

-6y-y = 7

-7y =7

divide both sides by -7

-7y/-7 =7/-7

y = -1

put the value of y=-1 in equation 3

x = -3yequation3

x = -3(-1)

x= 3

therefore the value of x and y are 3 and -1 respectively

d. 24+-0.114

step-by-step explanation:

the question requires us to calculate the approximate 95% confidence interval for the mean number of ounces of ketchup per bottle in the sample given the following statistics;

sample mean = 24

standard deviation, σ = 0.4

sample size , n = 49

the confidence interval for a population mean is calculated using the formula;

sample mean ± z-score*(σ/sqrt(n))

the z-score associated with a 95% confidence interval, from the standard normal tables, is;

1.96

substituting these values into the formula;

24 ± 1.96*(0.4/7)

= 24 ± 0.112

from the alternatives given, choice d is closest to the above expression;

the answer is 13 cm