It’s challenging to demonstrate that on here unless I sketch a diagram for you... It’s important to recognize that 10 thousandths equates to 1 hundredth. If you draw a square measuring 100 by 100 centimeters on graph paper, it will include a thousand individual squares because 100 x 100 equals 1000, and if you shade 10 of those squares, that represents 10 thousandths.
The risk of down syndrome, in terms of the percentage of births per year, is changing at a rate given by the equation r(x) = 0.004641x² - 0.3012x + 4.9 for the range 20 ≤ x ≤ 45, where x signifies the maternal age at delivery. To derive the risk function as a percentage of births relative to maternal age x, we integrate r(x), leading to the function f(x) = 0.001547x³ - 0.1506x² + 4.9x + c. When x is 30, f evaluates to 0.14%. This means that 0.001547(30³) - 0.1506(30²) + 4.9(30) + c equals 0.14. Solving gives 41.769 - 135.54 + 147 + c = 0.14, which simplifies to c = -53.089. As a result, we establish that f(x) = 0.001547x³ - 0.1506x² + 4.9x - 53.089 for 20 ≤ x ≤ 45. The graph corresponding to this function is illustrated below.
There are a total of 20,000 available numbers. To ascertain how many phone numbers are available, the number of digits in each number must be known. Here, I will assume each number has 7 digits. This leads to the format starting with either 373XXXX or 377XXXX, where each X can be any digit from 0 to 9. This results in 10 options for each X. Therefore, there are 10×10×10×10 = 10,000 distinct phone numbers starting with 373 and another 10,000 with 377, totaling 20,000 numbers.
Indeed, a fare of $40 is a fair charge for the cab ride.
Explanation
Sheri's cab fare totaled $32, with a gratuity rate of 20%.
The gratuity amount is: 
Thus, the total cab fare including gratuity is: 
Since Sheri issued a $40 check to the cab driver, it indicates she provided ($40 - $38.40) or an extra $1.60 to the cab driver. Consequently, the $40 payment is reasonable for the cab fare.
