Two different alloys are being considered for making lead-free solder used in the wave soldering process for printed circuit boards. a crucial characteristic of solder is its melting point, which is known to follow a normal distribution. a study was conducted using a random sample of 21 pieces of solder made from each of the two alloys. in each sample, the temperature at which each of the 21 pieces melted was determined. the mean and standard deviation of the sample for alloy 1 were = 218.9

Which of the following statements is true? a. the irrational number system is not closed under multiplication, because the product of two irrational numbers is always a rational number. b. the irrational number system is not closed under multiplication, because the product of two irrational numbers is not always an irrational number. c. the irrational number system is closed under multiplication, because the product of two irrational numbers is always an irrational number. d. the irrational number system is closed under multiplication, because the product of two irrational numbers is always a rational numbers. reset submit