Which tern of the series 27, 24, 21, 18, 15, ..... is the first negative term.

M4maths Previous Puzzles

05 Apr 2016 First negative term

Which tern of the series 27, 24, 21, 18, 15, ..... is the first negative term.

OPtion

1) 9
2) 7
3) 16
4) 11
5) 15
6) 14
7) 10
8) 13
9) 12
10)8

Solution

Here a = 27 and d = 24-27 = -3 (Series is AP)
Let nth tern of the given AP be the first negative tern
Then Tn < 0
=> (a + (n-1)d) < 0
=> (27 + (n-1)(-3)) < 0
=> (27 - 3n + 3) < 0
=> 30 - 3n < =
30 < 3n
3n > 30
n > 10
Therefore n = 11
Hence, the 11th tern is the first negative tern of the give AP.
Option 4)

Correct Option: 4 Best Solution (17)

Mukund Manohar   8 years AGO

The difference in every number d=-3
11th term = 27 +(11-1)*(-3)
=27-30
=-3
So 11th term is the first negative term

Like? Yes (3) | No (1)  

RAHUL KUMAR   8 years AGO

As the first negative number of the series is -3
so there are 11 term from 27 to -3.
Option (4) is the ans.

Like? Yes (1) | No (1)  

dev   8 years AGO

27, 24, 21, 18, 15, 12, 9, 6, 3, 0, -3

so 11th term is the first negative number. so option (4)

Like? Yes (4) | No (4)  

Karthik   8 years AGO

27,24,21,18,15,12,9,6,3,0,-3,....
-3 is the first negative term.
It is at 11th position.

Like? Yes (2) | No (2)  

soundarya   8 years AGO

considering 0 as the last term, applying the formula, of A.P
n=[(l-a)/d]+1, where l=0; a=27;d=-3,
we get n=10;
therefore the first negative term would be the 11th term.

Like? Yes (2) | No (2)  

tasho k   8 years AGO

suppose it is nth term
first neg term will be -3.
by using arithmetic progression
27=-3+(n-1)*3
solving this n=11

Like? Yes (1) | No (2)  

Priya Verma   8 years AGO

the first negative term will be -3 which is 11th term of the series ( difference between the terms of the series is 3)

Like? Yes (1) | No (2)  

CHANDAN KUMAR   8 years AGO

27,24,21,18,15,12,9,6,3,0,-3
so , 11th term is first negative term.
correct options is 4) 11

Like? Yes (1) | No (2)  

ABHINAV PUSHPAM   8 years AGO

The series is a AP with negative common difference (-3) , first term, i.e a=27, and d= -3.
let An be the first negative term.
then, An

Like? Yes (4) | No (8)  

Meenakshi   8 years AGO

In the given A.P series a=27 d= -3
Let n be the first negative term then
27+(n-1)(-3) < 0
30-3n

Like? Yes | No (4)  

SANTOSH KUMAR DASH   8 years AGO

27 =1st term
24=2nd erm
.
.
.
.
.
.
-3=11therm

Like? Yes | No (4)  

aayushi tomar   8 years AGO

a=27,d=-3
so 0=27+(n-1)-3
n=10,so first negative term will be -3 n it will b 11th term

Like? Yes | No (4)  

HARIBASKAR   8 years AGO

27
24
21
18
15
12
9
6
3
0
-3


term = 11

Like? Yes (1) | No (5)  

viswambher   8 years AGO

every term in the series is being reduced by 3 so the series is
27 24 21 18 15 12 9 6 3 0 -3
and the 1st negative term is -3 which is also the 11th term in the series

Like? Yes | No (5)  

Anee Verma   8 years AGO

x = a + (n-1) d
x = no. in series
a = 1st no. in series
n = sequence no. of x in series
d = difference between 2 nos in the series
In our question,
x = -3 (because it -3 will be the first negative no. as all nos are decreasing by 3)
a = 27
n = n
d = -3

Solving the equation, gives n = 11

Like? Yes (1) | No (6)  

Dinesh kumar sah   8 years AGO

In the given series 1st negative number is -3 and if we count the number of terms up to this -3,then there are 11 terms in the above series . So option (4) is the right answer.

Like? Yes | No (5)  

THUMMALA VINEESHA   8 years AGO

27+(n-1)*(-3)30
n>10
so n=11
option 4

Like? Yes | No (5)