next number of the series 1.2 + 2.16 + 5.184 + 15.552 + ................. will be

M4maths Previous Puzzles

07 May 2012 series

next number of the series
1.2 + 2.16 + 5.184 + 15.552 + ................. will be

OPtion

1) 46.8766
2) 55.9872
3) 58.9682
4) 58.9932
5) 64.4532
6) 68.7764
7) 72.3332
8) 76.9682
9) 77.8972
10) none of these

Solution

The series is
1.2
1.2*1.8
1.2*1.8*2.4
1.2*1.8*2.4*3.0
1.2*1.8*2.4*3.0*3.6

Correct Option: 2 Best Solution (13)

kalaiarasan   12 years AGO

1.2 (it is come from (1*12)/10)(12 add with 6=18..next multiplying number is 18)
next 2.16= (1.2 * 18)/10 (afterwads 18 is added with 6 so 24 is next multiplying number on..)
5.184=(2.16 * 24)/10 (next 24+6=30)
15.552=(5.184 * 30)/10 (next 30+6=36)
55.9872=(15.552 * 36)/10......

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Vignesh   12 years AGO

1.2 *1.8 = 2.16
2.16 *2.4 = 5.184
5.184 *3.0 = 15.552
15.552 *3.6 = 55.9872

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shyoram Gurjar   12 years AGO

series is

1.2 * 1.8 =2.16
2.16 * 2.4 =5.184
5.184* 3.0 =15.552
15.552* 3.6 =55.9872

Hence correct answer is option 2

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chiru   12 years AGO

2.16/1.2=9/5;
5.184/2.16=12/5;
15.552/5.184=15/5=3;
hence x/15.552=18/5
=> x=55.9872

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Niraj   12 years AGO

2.16/1.2 = 1.8
5.184/2.16 = 2.4 (2.4=1.8+.6)
15.552/5.184 = 3 (3=2.4+.6)
x/15.552 = 3.6 (3.6=3+.6)

=>x=55.9872

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Narayan Regmi   12 years AGO

1.2
1.2*1.8
1.2*1.8*2.4
1.2*1.8*2.4*3.0
1.2*1.8*2.4*3.0*3.6

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Flower   12 years AGO

multiples are increasing by 0.6
when we divide first two no's ,we will get 1.8
and when we divide 3rd no by 2nd no we get 2.4 and therefore every time multiples are added by 0.6

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Devendra Marghade   12 years AGO

The series is a terms multiplied by previous one by the difference of 0.6
1.2* 1.8=2.16
2.16*2.4=5.184
5.184*3=15.552
15.552*3.6=55.9872

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sumanth jayam   12 years AGO

1.2 * 1.8 = 2.16
2.16 * 2.4 = 5.184
5.184 * 3.0 = 15.552
15.552* 3.6 = 55.9872

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appu.srva   12 years AGO

2.16/1.2 = 1.8 {i.e. 0.6 * 3}
5.184/2.16 = 2.4 {i.e. 0.6 * 4}
15.552/5.184 = 3.0 {i.e. 0.6 * 5}
X/15.552 = 3.6 {i.e. 0.6 * 6}

So X is 55.9872.

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Rakesh Kumar Kohli   12 years AGO

Explanation: Let t(n) denotes the nth term, where n = 1,2,3,4,5,.......
t(1) = 1.2 and
t(n)= t(n-1)*(n+1)*0.6 for n>=2, thus

t(2)=t(2-1)*(2+1)*0.6=t(1)*1.8=1.2*1.8 = 2.16
t(3)=t(3-1)*(3+1)*0.6=t(2)*2.4= 2.16*2.4 =5.184
t(4)=t(4-1)*(4+1)*0.6=t(3)*3.0=5.184*3.0 =15.552
t(5)=t(5-1)*(5+1)*0.6=t(4)*3.6=15.552*3.6 =55.9872

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krishnamurthy   12 years AGO

2.16/1.2=1.8
5.184/2.16=2.4
15.552/5.184=3
55.9872/15.552=3.6

the result will increase 0.6 every time

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vinay upadhyay   12 years AGO

(2.16-1.2)/1.2 = .8
(5.184-2.16)/2.16=1.4
(15.552-5.184)/5.184=2
.8, 1.4, 2, it must be 2.6
hence
(x-15.552)/15.552=2.6

therefore,
x=55.9872

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