The length of a rectangle is 3 inches less than its twice the width. If the perimeter is 78 inches, what is its width?

first lets write the formula for the perimeter of a rectangle: P = 2L + 2W or Perimeter = 2*Length + 2*Width

Now lets write the information that we know form the problem given:

We are told that the Perimeter = 30 inches  

We are told that the Length is 3 inches less than twice its width. So lets rewrite this one into the equation. The length (L) is equal to (=) 3 inches less (-3) than twice its width (2W). Therefore, L = 2W-3

So now we have an equation to plug in for L and we still do not know what W is  

Next, Plug into the equation!

P = 2L + 2W

30 =  2 (2W-3) +2W

Now Solve!

30 = 2 (2W-3) +2W

30 = 4W-6+2W

+6          +6

36 = 4W + 2W

36 = 6W

6 = W

Now we know what W is we can plug in to find L

P = 2L + 2W

30 = 2L + 2(6)

30 = 2L + 12

-12  -12

18 = 2L

9 = L

The length of the rectangle is 9 inches!

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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