Myra is evaluating the expression –31.7 + 4.5x, when x = 2.1. –31.7 + 4.5(2.1) –27.2(2.1) –57.12 what was myra’s error?

Myra's Error: Addition instead of multiplication

Correct -22.25

Step-by-step explanation:

Myra is evaluating the expression.

Expression: -31.7 + 4.5x  for x=2.1

Step 1: Put x=2.1 into expression            

      Myra's Steps                               Correct Step

    -31.7 + 4.5(2.1)                            -31.7 + 4.5(2.1)

Thus, first step correct.

Step 2: Simplify 4.5(2.1) by multiply

      Myra's Steps                               Correct Step

          -27.2(2.1)                                -31.7 + 9.45

Thus, second step incorrect.

Therefore, Myra's error in second step. She did addition(-31.7+4.5)  instead of multiplication(4.5×2.1)

Step 3: Combine like terms

-31.7 + 9.45 = -22.25

Hence, The correct answer of the given expression is -22.25  

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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