A box contains 5 blue, 4 red, and 3 yellow marbles. Two marbles are randomly drawn and not replaced. What is the probability of drawing a blue then a red marble? 5/36
20/130
1/66
5/33

the answer is 5/33

Step-by-step explanation:

Total marbles = 5 blue + 4 red + 3 yellow = 12

Two marbles are selected, first is blue which gives us :

5/12 --eq 1

Then red marble is selected ( note: one marble is already drawn and not replaced so we have a total of 11 marbles )

The probability of red gave us :

4/11 --eq 2

Now we multiply eq 1 and 2

5/12 x 4/11 = 5/33

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)