Hi there,
In order to solve this, we have to know what Moore's law is. Moore's Law states that the number of transistors in an IC (Integrated Circuit) doubles every two years. Since the density doubles every two years and there are 3 two year periods between 1970 and 1976, we would multiply 1,200 by 2 to the power of the number of two year periods. In this case, that would look like 1,200*2³. Since 2³ is equal to 8, we can rewrite this as 1,200*8. Multiplying these, we get 9,600, thus, there would be 9,600 transistors in a computer chip during 1976.
Have a good night,
Jamie