The average salary of a sales lady in malls in Metro Manila is P 430/ a day. Assume a normal distribution with a standard deviation of P 80.What is the probability that a random selected sale lady is receiving a daily salary bigger than 500?

b. For a sample of 30 sale lady, what is the probability that the sale lady’s salary is smaller than P 400 in a day?

a.) Let be a random variable representing the salary of a saleslady in malls in Metro Manila, then the probability that is less than a value is given by , where is the population mean and is the population standard deviation.

Here, , .

Thus, the probability that a randomly selected sale lady is receiving a daily salary bigger than 500 is given by

Using the table of areas under the standard normal curve or a calculator, we have .

Therefore, the probability that a randomly selected sales lady is receiving a daily salary bigger than 500 is 0.19079.

b.) Let be a random variable representing the average salary of a saleslady in malls in Metro Manila from a sample of size , then the probability that is less than a value is given by , where is the population mean and is the population standard deviation.

Here, , , and .

a.) Thus, the probability that the saleladys’ average salary is smaller than P 400 in a day is given by

Using the table of areas under the standard normal curve or a calculator, we have .

Therefore, the probability that the saleladys’ average salary is smaller than P 400 in a day is 0.01999.

b.) The probability that the mean of private vehicles ages is over 6 years is given by

Using the table of areas under the standard normal curve or a calculator, we have .

Therefore, the probability that the mean of private vehicles ages is over 6 years is 0.5.