Answer:25
Step-by-step explanation:
Answer/Step-by-step explanation:
Area of trapezium = ½*(AD + BC)*AB
Area = 42 cm²
AD = (x + 8) cm
BC = (x + 5) cm
AB = x cm
Plug in the values into the equation
42 = ½((x + 8) + (x + 5))*x
42 = ½((x + 8 + x + 5)*x
42 = ½(2x + 13)*x
Multiply both sides by 2
42*2 = (2x + 13)*x
84 = 2x² + 13x
2x² + 13x = 84
Subtract both sides by 84
2x² + 13x - 84 = 0
Note that 60 minutes is 1 standard deviation away from the mean and from recalling the 68-95-99.7 rule, the area that will remain is (100 - 68) = 32%. However, we only want the leftmost portion of this area, so the answer is 32%/2 = 16%.
<span>Choose D.</span>
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