In a multiple choice examination of 20 questions, four marks are given for each correct answers and one mark is deducted for each wrong answer. There is no penalty for not attempting a question. a candidate attempts "a" questions and get "c" correct. Write down, and simplify, an expression for the candidate's total mark in terms of "a" and "c".

Step-by-step explanation:

Total no. of questions = 20

Marks given for a correct answer = 4

Marks deducted for a wrong answer = 1

No. of questions attended by the candidate = a

No. of questions the candidate gets correct = c

No. of questions the candidate gets wrong = a - c

Marks obtained for correct answers = 4c

Marks deducted for wrong answers = 1 (a - c)

Total marks scored by the candidate =

Marks obtained for correct answers - Marks deducted for wrong answers

Total marks scored by the candidate = 4c - 1 (a - c)

= 4c - a + c

= 5c - a

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.