Answer:
a) We know that atleast one or more author writes a book.
Symbol to indicate one or more is (B)
So the correct option is B
b) We know that zero to multiple books are written by any author.
Symbol to indicate zero or more is (A)
So the correct option is A
c) The fourth option is correct if we replace by many to many relationship and generate a new entity.
So the relationship betweem author and contract is one to many. So we know that there is atleast one author that represent in symbol d and books has atleast 0 that represent in symbol c.
So Fourth Option is correct d at blue side and c at red side.
d) There are two forirgn keys in table Contract one is from AuthorId and other is ISBN.
So correcct option is C
No they don’t have the same data format.
Answer:
Early school starting times cause poor performance on tests, inattention in class, and drowsiness.
Explanation:
Carskadon study on early school starting time showed that it cause increased rate of rapid eye movement sleep in students and they doze off during lecture. Insufficient sleep lessens attentiveness levels in the class which affects students' potential to learn. The study showed that students do not perform well on tests. In addition to the difficulty in learning, there is an increased danger of accidents for those who drive to school due to dizziness.
Answer:
The solution code is written in Python:
- sec = int(input("Enter number of seconds: "))
-
- if(sec >=60):
- min = sec // 60
- sec = sec % 60
- else:
- min = 0
-
- print(str(min) + " minutes " + str(sec) + " seconds")
Explanation:
Firstly, use input function to prompt user to enter number of seconds and assign the input value to variable sec (Line 1).
Next, create an if statement to check if the sec is bigger or equal to 60 (Line 3). If so, we user // operator to get minutes and use % operator to get the seconds (Line 4 - 5).
Then we use print function to print the minutes and seconds (Line 9).
