Marks brother is nine years older then mark. their combined ages add up to 33. how old is mark

12 yrs old

Step-by-step explanation:

Mark(M)+Brother(B)=33

M=B-9

therefore

(B-9)+B=33

2B-9=33

2B=33+9

2B=42

B=21

21-9=M

M=12

Mark is 12 years old

Step-by-step explanation:

a=brothers age

(9+a)+a=33

(9+12)+12

(21)+12=33

a=12

Mark is 12 years old

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;