How would I simplify these expressions? (Pre-Calculus) I know that you are supposed to multiply all of these to do so, but every time I do that, I still get the wrong answer. My textbook says that these are the answers: 19: -15 + 8i
21: 8 + 6i
23: 34
25: 85
Could anyone explain how they got these answers? Mine are way off. Is the book just wrong? In #21, how would 3 times 3 equal 8 in the answer? Am I missing something?

answer: it's upside down and i can't read it

step-by-step explanation:

hello,

b) 62.47% of the students are between 14 and 18 years old.

step-by-step explanation:

mean = 15 and standard deviation = 2

student between 14 to 18

formula used z-score

for age 14 , z score

using z-table , p(z> -0.5)=0.3085

for age 18 , z score

using z-table , p(z< 1.5)=0.9332

p(-0.5< z< 1.5)=0.9332-0.3085 = 0.6247

thus, 62.47% of the students are between 14 and 18 years old.

click to let others know, how is it

0.0

0 votes

1

report

read more on -

step-by-step explanation: