急!谁能帮我翻译一下这几道数学题目!非常急!1.Thehalf-lifeofacertainradioactivesubstanceis2.5sec.TheinitialamountofsubstanceisS。grams.a.ExpresstheamountofsubstanceSremainingasafunctionoftimet.b.Howmuchoft

Question

急!谁能帮我翻译一下这几道数学题目!非常急!
1.The
half-life of a certain radioactive substance is 2.5 sec.The initial amount of
substance is S。grams.
a. Express the amount of
substance S remaining as a function of time
t.
b. How much of the substance isleft after 2.5 sec? after 7.5 sec?
c. Determine S。if there was 1 g left after 1 min.
2. If juan
invests$12,500 into a retirement account with a 9&interest rate compounded
continuously, how long will it take this single payment to triple in value?
3. The bearing
of two points on the shore from a boat are 115° and 123°.Assume the two points are 885 ft apart.How far is the boat from the
nearest point on shore is straight and runs north-south.
4. Find the
radian measure of the largest angle of the triangle whose sides have lengths 8,9, and 10.

Answer 1

1.这种物质的半衰期是2.5秒.一开始有S.克的这物质,
a.写出剩余量S用t的表达式.
b.2.5秒后,剩多少?7.5秒呢?
c.如果1分钟后剩余量为1g,求S.
2.If juan
investsinto a retirement account with a 9&interest rate compounded
continuously,how long will it take this single payment to triple in value?
如果这个人投资$12,500 在一个退休账户,9%的利息率,复合连续,（这个计利息的方法我不知道,我翻译的这个不是专业的哈）,多长时间之后当拿到的钱是最初三倍?
3.读最后一句话不明白,在发下哈
4.用弧度制表达这个三角形的最大的角,三角形三边分别是8,9,10.