Write a function called getCylinderVolume to return the volume of one cylinder. This function has two parameters to specify the cylinder's radius and height. Requirement: The value of pi shall be defined as one constant variable inside this function. Write a function called getGradeLetter to return the letter grade from an integer score. The grade scale to be used is defined as follows: Write a function called getAvgValidScore to return the average value of valid scores from an input array of scores for whole class. Requirement: This function shall be able to handle flexible array size; do NOT change the score array