Half life is the time taken for half a quantity of a substance to decay . fermium (atomic number 100 ) has 19 isotopes , most of which have half-lives if less than a second .

from the Fermium 257, he's got 100Kgs of Fermium 252, and Fermium 253.

the 252 is 40%, well, 40% of 100 is just 40, so 40 of Fermium 252, with a half-life of 1 day.

and 60% of 100 is just 60, so 60Kgs of Fermium 253 with a half-life of 3 days.

from August 31st to September 15, that'd be 15 days later, so how much is left altogether after 15 days.

john has 55 candy left.

walter needs to make at least 5 more cookies but no more than 40. 5 ≥ x ≥ 40;

step-by-step explanation:

walter has to make a minimum of 20 cookies. he already has 15 cookies made, so he must make 5 more to meet the minimum.

the maximum amount of cookies he can make is 55. he already has 15, so he has to make no more than 40 more cookies to meet the maximum.