Question 4 a) Explain, with an example, how the use of multithreading enables a program to run faster. Use pseudocode or actual code to illustrate your answer. b) The following is non-concurrent code for working out the cosine of a sequence of integers. Rewrite this in Python so that it is concurrent. Your program must return the results in the order of the input sequence. This code is available with this TCA as Q4.zip. import math values = [12,20,4,100,64,77,200,9,10] def mycosine (n) : woonwww. return math.cos(n) ww wwwwwwww def non concurrent cosines(): wwwww for val in values: wwwww res = mycosine (val) wwwww print('Cosine of %s is %s' % (val,res), '\n') non concurrent cosines () wwwwww c) Use Python's datetime function to time the execution of the concurrent code, and to print out the result. Add the lines of code that support this to your solution to Question 4 (b). 1 import math 2 3 values = [12,20,4,100,64,77,200,9,10] 4 5 def cosine(n): 6 67 7 V return math.cos(n) 8 ✓ def non_concurrent_cosines(): v 9 v 10 11 12 for val in values: res = cosine(val) print('Cosine of %s is %s' % (val, res), '\n') 13 non_concurrent_cosines() 14

1. Consider the loop from Section 8.3 of your textbook. prefixes = 'JKLMNOPQ'suffix = 'ack' for letter in prefixes:     print(letter + suffix) Put this code into a Python script and run it. Notice that it prints the names "Oack" and "Qack". Modify the program so that it prints "Ouack" and "Quack" but leaves the other names the same. Include the modified Python code and the output in your submission. 2. Give at least three examples that show different features of string slices. Describe the feature illustrated by each example. Invent your own examples. Do not copy them for the textbook or any other source.     The code and its output must be explained technically. The explanation can be provided before or after the code, or in the form of comments within the code. For code modification type of questions, always mention or clearly highlight the part which is modified, along with the reason stated, as a code comment. The descriptive part of your response must be at least 200 words. If you…

What does the following Python code print to the terminal? (Assume we run this as a complete snippet of code. Be precise with any delimiters like commas, parenthesis, etc.) 1st = (4, 9, 16) for i in range (len(lst)): 1st[i] = lst[i] + 1 print(lst) 4 9. 16 O 4, 9, 16 O 5 10 17 O Error. Tuples are immutable

QUESTION 17 If program code references an invalid array index value, when is an error message generated? a. An error occurs during execution. b. An error occurs when the program is compiled. c. No message is generated since Java provides no error checking for this problem. d. An error occurs after execution is completed.