a$)$ Write a function called readArray$()$ that will accept a double array of size $100$ as its only parameter and will prompt for and read in $100$ values into the array.

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b$)$ Write a function called avg$()$ that will accept a double array of size $100$ as its only parameter and will calculate and return the average of the $100$ numbers stored in the array.

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c$)$ Write a function called var$()$ that will accept two parameters $$ a double array of size $100$ and a

double value, the average of the array values. It will then calculate and return the variance of the values stored in the array. Here is a description of how to calculate the variance: If we denote the array values as x$1,$x$2,,$x$10,$ and denote the array value average as x$,$ then

$$the$$variance$=($x$1-$x$)2+($x$2-$x$)2++($x$100-$x$)2100.$

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