Solving type error issue with python list

I am trying to graph the output of serial and parallel execution times but keep getting

TypeError: unsupported operand type(s) for /: 'list' and 'list'.

How do i divide contents of the list so so i don't get this error

TypeError Traceback (most recent call last) in 49 50 # Compute the ratio of these times ---> 51 ratio.append(serialTime/parallelTime) 52 53

TypeError: unsupported operand type(s) for /: 'list' and 'list'

import numpy as np
import multiprocessing as mp
import time
import matplotlib.pyplot as plt

# Sleep for t seconds
def burnTime(t):
    time.sleep(t)

# Main
if __name__ == '__main__':
    N = 16 # The number of jobs
    P = 4  # The number of processes

    # A thread pool of P processes
    pool = mp.Pool(P)

  # Use a variety of wait times
    ratio = []
    wait_time = [1, 2, 3, 4, 5, 6, 7, 8]

    #serial results    
    print("Serial Execution Times")
    for _ in range(N):
        start_time = time.time()
        serialTime = [burnTime(t) for t in wait_time]
        print("---- {} seconds ---- ".format(time.time() - start_time))


    print("\n")

    #parallel results
    print("Parallel Execution Times")
    for _ in range(N):
        start_time = time.time()
        parallelTime = pool.map(burnTime, wait_time)
        print("---- {} seconds ---- ".format(time.time() - start_time))



    for t in wait_time:
          pass
    # Compute jobs serially and in parallel
    # Use time.time() to compute the elapsed time for each
       # serialTime = 1
        #parallelTime = 1



    # Compute the ratio of these times
    ratio.append(serialTime/parallelTime)


    # Plot the results
    plt.plot(wait_time, ratio, '-ob')
    plt.xscale('log')
    plt.xlabel('Wait Time (sec)')
    plt.ylabel('Serial Time (sec) / Parallel Time (sec)')
    plt.title('Speedup versus function time')
    plt.show()

Output of SerialTime
---- 6.604194641113281e-05 seconds ---- 
---- 1.9073486328125e-06 seconds ---- 
---- 9.5367431640625e-07 seconds ---- 
---- 2.1457672119140625e-06 seconds ---- 
---- 2.1457672119140625e-06 seconds ---- 
---- 1.9073486328125e-06 seconds ---- 
---- 9.5367431640625e-07 seconds ---- 
---- 2.1457672119140625e-06 seconds ---- 
---- 1.9073486328125e-06 seconds ---- 
---- 9.5367431640625e-07 seconds ---- 
---- 1.1920928955078125e-06 seconds ---- 
---- 2.1457672119140625e-06 seconds ---- 
---- 1.9073486328125e-06 seconds ---- 
---- 1.1920928955078125e-06 seconds ---- 
---- 2.1457672119140625e-06 seconds ---- 
---- 1.9073486328125e-06 seconds ---- 

output of ParalleTime
---- 12.006800889968872 seconds ---- 
---- 12.004575967788696 seconds ---- 
---- 12.00544810295105 seconds ---- 
---- 12.006248950958252 seconds ---- 
---- 12.003881216049194 seconds ---- 
---- 12.005573749542236 seconds ---- 
---- 12.003982067108154 seconds ---- 
---- 12.003642082214355 seconds ---- 
---- 12.004355192184448 seconds ---- 
---- 12.00377106666565 seconds ---- 
---- 12.003960132598877 seconds ---- 
---- 12.004532098770142 seconds ---- 
---- 12.003446578979492 seconds ---- 
---- 12.003416776657104 seconds ---- 
---- 12.004649877548218 seconds ---- 
---- 12.004476070404053 seconds ----