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wondefoo

Muthu started working for a company on 1 Jan 2002 with an initial annual salary of RM18000.
Every January, the company increased his salary by 5% of the previous year's salary. Calculate

a) his annual salary, to the nearest RM, for the year 2007

b) the minimum value of n such that his annual salary in the nth year will exceed RM36000

c) the total salary, to the nearest RM, paid to him by the company, for the year 2002 to 2007.

Allmaths

Muthu started working for a company on 1 Jan 2002 with an initial annual salary of RM18000.
Every  ...
wondefoo 发表于 7-2-2012 01:44 PM

(a)
Year 2002, T1=18000
Year 2003, T2=18000+18000(0.05)=18000(1.05)
Year 2004, T3=18000(1.05)+18000(1.05)(0.05)=18000(1.05)^2

         .
         .
         .
Year 2007, T6=18000(1.05)^5
                        =22973.06813
                        =RM22973

(b)
Tn=18000(1.05)^(n-1)>36000
                        (1.05)^n>2.1
                                    n>(lg 2.1)/(lg 1.05)
                                    n>15.2067
                                    n=16

(c)Sn=18000(1.05^n-1)/(1.05-1)
     S6=18000(1.05^6-1)/0.05
     S6=122434.43
     S6=RM122434

wondefoo

回复 2# Allmaths

谢谢你，还有两题我不知道我的答案对不对，可以帮我解吗？
it is given that 1, x^2,x^4,x^6,...is a g.p. and its sum to infinity is 3. Find
a)the common ratio in terms of x
b)the positive value of x

the sum of the first n terms of an A.P. is given by Sn=n/2[3n+1].Find
a) the sum of the first five terms
b)the 5th term

Allmaths

回复  Allmaths

谢谢你，还有两题我不知道我的答案对不对，可以帮我解吗？
it is given that 1, x^2,x ...
wondefoo 发表于 7-2-2012 02:00 PM

    刚帮你解了， 去Add Maths功课讨论区查看