The decay of 40K to 40Ar is used to date igneous rocks around fossil deposits to bracket the age of the fossils. When 40K decays, 10.9% of the time it produces 40Ar. The half-life of 40K is 1.248 x 109 years. In a given rock sample, 281.8 nmol of 40K is measured and 7.25 nmol of 40Ar is measured. What is the age of the rock in years

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .

Wagons/motorized vehicles

Answer is (d)a brainliest would be appreciated