Observe the sequences below.
1. -3, 1, 5,9,-
ii. 1, 2, 4, 8, ..
iii. 4, -12, 36, -108,
iv. 7, 14, 21, 28, -
which of these are arithmetic sequences?
a.
ii and iii
ob, i and iv
c.
i, ii, and iv
d.
iv only

C

Step-by-step explanation:

-3,1,5,9. Sequence: Add 4

1,2,4,8  Sequence: Double previous

4,-12,36,-108 Sequence: ???

7,14,21,28 Sequence: Add 7

B

Step-by-step explanation:

i) -3,1,5,9 is in arithmetic progression with common difference of 4

ii) 1,2,4,8... is not in AP it is rather in geometric progression with common ratio 2

iii) 4, -12, 36, -108... the given sequence id neither in AP or GP

iv) 714,21,28 is again in AP with Common difference 7

hence i and iv are in AP therefore option B is correct

answer: first option i.e. 'a' is correct.

step-by-step explanation:

since we have given that

number of minutes to wrap a small gift box = 4 minutes

we need to find the number of gifts to be wrapped in 5 minutes

since there is a direct variation, as the number of minutes will increase with   number of gifts to be wrapped.

so, let the number of gifts to be wrapped in 5 minutes be x.

so, it becomes,

hence, first option 'a'   is correct.