The answer is D) isosceles and equilateral triangle
On your calculator, use the normalcdf() function, enter the Lower Limit, Upper Limit, Mean, and Standard deviation.
The mean and standard deviation are given to you. You want to find "less than 13.5 seconds", meaning that 13.5 is the maximum "Upper Limit" and 0 would be the Lower Limit because we can pretend 0 second is the minimum. Don't worry about negatives, in this scenario, values like "-5 seconds" are impossible.
Enter normalcdf(0, 13.5, 13.56, 2.24) in a calculator and the output result is the answer.
Explanation:
At each step, the product of the quotient digit and the divisor is subtracted from the dividend. This gives you the new dividend.
When the quotient digit is 7, the product of 7 and 5 is subtracted from the dividend. The dividend at that point is 35, so you have 35 - 35 = 0. The 0 is the next dividend. Among other things, that tells you you're done. (Any additional quotient digits will be zero.)