Answer:
25
Step-by-step explanation:
9+13+3 = 25
__________
Answer:
41 6/10 or 41 3/5
both answered are the same, just simplified it
Step-by-step explanation:
20 4/5 x 2= 41 6/10 or 41 3/5
Answer:

Step-by-step explanation:
we are given half-life of PO-210 and the initial mass
we want to figure out the remaining mass <u>after</u><u> </u><u>4</u><u>2</u><u>0</u><u> </u><u>days</u><u> </u>
in order to solve so we can consider the half-life formula given by

where:
- f(t) is the remaining quantity of a substance after time t has elapsed.
- a is the initial quantity of this substance.
- T is the half-life
since it halves every 140 days our T is 140 and t is 420. as the initial mass of the sample is 5 our a is 5
thus substitute:

reduce fraction:

By using calculator we acquire:

hence, the remaining sample after 420 days is 0.625 kg
Answer:
36, 60, 84
Step-by-step explanation:
3+5+7=15
180/15=12
12*3=36
12*5=60
12*7=84