Percentage :
1. If the yearly depreciation rate of a machine is 40% , its value after 2 years will decrease by ? % ?
2. Darwin would like to make an investment. A bank offers a plan with an interest rate of 6 % p.a. compounded half - yearly. If he would like to earn $4000 interest after 2 years , how much should he invest ?
3. Felix borrows $36 000 from a bank at the beginning if this month at an interest rate of 21 % p.a. compounded monthly . If he repays $12400 at the end of each month, can he settle the loan after 3 repayments ? If not , how much does he still owe the bank ?
Probability:
1. In an examination , there are 20 multiple choice questions, To prevent students from choosing an answer randomly , X marks will be deducted for each wrong answer, and 5 marks will be given for each right answer.Assume that each question has 5 choice .
(a) If all question in the exam are answered at random , what is the expected value of the marks of each question ?( express youe answer in terms of X )
(b) If all question in the exam are answered at randim , what is the expected value of the examination marks ? ( express your answer in terms of X )
(c) If the teacher expectx the students who have answered all question at random to get zero marks, find the value of X .
可5可以將所有steps 列出同解釋點解會咁計??Thank you so much !!!!!!!!!