The half-life of radium is 1690 years. If 90 grams are present now, how much will be present in 400 years?

76.38 g

Step-by-step explanation:

Below expresion can be used in calculating the remaining amount of radium

A(t)=A(0) (1/2)^(t/h)

Let A(t)=the remaining amount of radium

Let A(0)= amount of radium at the beginning= 90 grams

t= amount of time in years= 400 years

h=the half-life time= 1690 years

A(t)=A(0) (1/2)^(t/h)

If we substitute the values into the expresion we have

A(t) = 90 × (1/2)^(400/1690)

A(t)= 76.38 g

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step-by-step explanation:

a formal letter is a letter the you would send to a king

step-by-step explanation:

5×5×5+2(8)÷2(2)+3(3)

15+16÷4+9

31÷13

do 31÷13 and u will get ur answer