Carbon-14 is a radioactive isotope of carbon that is used to date fossils. There are about 1.5
atoms of cafbon-14 for every trillion atoms of carbon in the atmosphere, known as 1.5 ppt
(parts per trillion). Carbon in a living organism has the same concentration as carbon-14. When
an organism dies, the carbon-14 content decays at a rate of 11.4% per millennium (1000 years).
Write an equation for carbon-14 concentration (in ppt) as a function of time (in millennia) and
determine how old a fossil must be that has a measured concentration of 0.3 ppt.

2. angles qrt and qst both measures 156 degrees.

step-by-step explanation:  

we have been given a diagram of a circle and we are told that measure of arc qvt is 156 degrees.  

we can see from our given diagram that angle qrt and angle qst subtends to arc qvt.

since we know that angles subtended by the same arc at the circumference are always equal.

by angle subtended by same arc theorem, measure of angle qrt and angle qst will be equal to the measure of arc qvt.

therefore, angles qrt and qst both measures 156 degrees and 2nd statement is the correct choice.

54 km / hours

step-by-step explanation:

we need to convert seconds to hours

60 seconds = 1 minutes

60 minutes = 1hour

15 m         60 second   60 minutes

  * *         = 54000 meters/ hour

second     1 minute             1 hour

now we need to convert meters to km

1000 m = 1 km

54000 m       1 km

*   = 54 km / hours

hour               1000m