Question ID: e1391dd6
Assessment Test Domain Skill Difficulty
SAT Math Advanced Math Nonlinear functions Medium
Question
According to Moore’s law, the number of transistors included on microprocessors doubles every 2 years. In 1985, a microprocessor was
introduced that had 275,000 transistors. Based on this information, in which of the following years does Moore’s law estimate the number of
transistors to reach 1.1million?
Answer
A. 1987
B. 1989
C. 1991
D. 1994
Rationale
Choice B is correct. Let x be the number of years after 1985. It follows that represents the number of 2-year periods that will occur within an
x-year period. According to Moore’s law, every 2 years, the number of transistors included on microprocessors is estimated to double. Therefore,
x years after 1985, the number of transistors will double times. Since the number of transistors included on a microprocessor was 275,000,
or .275 million, in 1985, the estimated number of transistors, in millions, included x years after 1985 can be modeled as . The year
in which the number of transistors is estimated to be 1.1 million is represented by the value of x when . Dividing both sides
of this equation by .275 yields , which can be rewritten as . Since the exponential equation has equal bases on each side, it
follows that the exponents must also be equal: . Multiplying both sides of the equation by 2 yields . Therefore, according
to Moore’s law, 4 years after 1985, or in 1989, the number of transistors included on microprocessors is estimated to reach 1.1 million.
Alternate approach: According to Moore’s law, 2 years after 1985 (in 1987), the number of transistors included on a microprocessor is estimated
to be , or 550,000, and 2 years after 1987 (in 1989), the number of transistors included on microprocessors is estimated to be
, or 1,100,000. Therefore, the year that Moore’s law estimates the number of transistors on microprocessors to reach 1.1 million is
1989.
Choices A, C, and D are incorrect. According to Moore’s law, the number of transistors included on microprocessors is estimated to reach
550,000 in 1987, 2.2 million in 1991, and about 6.2 million in 1994.