Question

120, 80,40,45,?,5 missing term

Answer 1

Answer:

The missing term of the series is 25.

Step-by-step explanation:

We are given the series,

120, 80, 40, 45, x, 5.

Now, as we see that,

120, 80, 40 is an alternating series with common difference $120-80=80-40=40$.

Thus, we need the series,

45, x, 5 to also be an alternating series.

That is, we get,

Common difference = $45-x=x-5$

i.e. $2x=50$

i.e. x= 25

Thus, the missing term of the series is 25.

Answer 2

Answer : 25

Step-by-step explanation:

Given, 120 , 80 , 40 , 45 , ? , 5

this series is the combination of two different series .e.g., 120, 80 , 40 and 45, ? , 5

here in 120, 80, 40 are in AP where common difference is -40.

so, 45 , ? , 5 should be arithmetic progression.

we know, difference between two consecutive terms of arithmetic progression always remains same.

Let unknown number is x.
then, x - 45 = 5 - x
or, x + x = 45 + 5
or, 2x = 50
or, x = 25

hence, required answer is 25.