Helllpp plz

Work Shown:

3r + 2 - r = -4b

(3r-r) + 2 = -4b

2r + 2 = -4b

2r+2-2 = -4b-2 subtracting 2 from both sides

2r = -4b-2

2r/2 = (-4b-2)/2 dividing both sides by 2

r = (-4b-2)/2

r = (-4b)/2 - 2/2 ... break up the fraction

r = -2b - 1

the 3rd option is right

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.

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step-by-step explanation: