Aradioactive isotope, phlebotinum, decays into dilithium with a half-life of 42 million years. if we find a rock with 25% phlebotinum to 75% dilithium, how old is the rock? how do we know?

time taken for 25% Phlebotinum and  75% Dilithium is 168 million years

Explanation:

radioactive isotope of Phlebotinum decays into Dilithium.

time taken to half life takes = 42 million years

half life means that the Phlebotinum is 50% and  Dilithium is also 50%

and now it is given that  Phlebotinum is 25% and Dilithium is 75%

hence this condition will come after two half lives.

for one half life it takes  42 million years

and for second half life time becomes 4 times of first half life

time for 25% Phlebotinum and  75% Dilithium is  = 4 × 42

     =  168 million years.

hence time taken for 25% Phlebotinum and  75% Dilithium is 168 million years

the proximity of water was an advantage to western europe and its culture was able to flourish as a result. trade and travel by sea were easier and safer in historical times.

1. there are no mountains to protect it from the sea

2. and its has wet cool summers and wet, mild winters.