Question

In a certain building at a top-secret research lab, some yttrium-90 has leaked into the computer analysts' coffee room. The leak would currently expose personnel to 150 millirems of radiation a day. The half-life of the substance is about three days; that is, the radiation level is only half of what it was three days ago. The analysts want to know how long it will be before the radiation is down to a safe level of 0.466 millirems a day. They would like a chart that displays the radiation level for every three days with the message Unsafe or Safe after every line. The chart should stop just before the radiation level is one-tenth of the safe level, because the more cautious analysts will require a safety factor of 10. The program should also print the first day that the room can be entered.

Problem Constants

SAFETY_FACT 10.0 /* the safety factor */
SAFE_RAD 0.466 /* the safe radiation level in millirems */

Problem Outputs

int day /* the day number*/
double radiation_level /* the radiation level in millirems*/

Additional Program Variables

double min_radiation /* the stopping level of radiation*/

Initial Algorithm

1. Compute the stopping level of radiation, that is the safe level divided by the safety factor
2. Prompt the user to enter the initial radiation level.
3. Compute and display the day number and the radiation level every three days that the radiation level exceeds the stopping radiation level. Also, indicate whether each level is safe or unsafe.
4. Display the day that the user can enter the room.
The program must have a function rad_table that takes in an initial radiation value, the minimum radiation (stopping level) and returns the day the user can enter the room.

** IN C LANGUAGE**

Answer 1

// do comment if any problem arises

//code

#include <stdio.h>

#define SAFETY_FACT 10.0

#define SAFE_RAD 0.466

// this function returns the day user can enter safely

int rad_table(double radiation_level, double min_radiation)

{

    int day = 0;

    while (radiation_level > min_radiation)

    {

        if (radiation_level <= SAFE_RAD)

        {

            return day;

        }

        day += 3;

        radiation_level /= 2;

    }

    return day;

}

int main()

{

    int day;

    double initial_radiation;

    double radiation_level;

    double min_radiation = SAFE_RAD / SAFETY_FACT;

    printf("Enter initial radiation level: ");

    // read initial radiation

    scanf("%lf", &radiation_level);

    initial_radiation = radiation_level;

    day = 0;

    // loop till radiation is reached minimum level

    while (radiation_level > min_radiation)

    {

        printf("\nRadiation level at day %d: %lf\n", day, radiation_level);

        printf("The radiation level is ");

        // check if radiation level is safe

        if (radiation_level <= SAFE_RAD)

            printf("safe\n");

        else

            printf("unsafe\n");

        // increement 3 days

        day += 3;

        // half life

        radiation_level /= 2;

    }

    printf("\nYou can enter the room at day %d\n", rad_table(initial_radiation, min_radiation));

}

Output: