The sum of the first 6 terms of a geometric series is
15, 624 and the common ratio is 5
what is the first term of the series?

4

Step-by-step explanation:

The sum to n terms of a geometric sequence is

=

where a is the first term and r the common ratio

Here r = 5 and a has to be found, thus

= , so

= 15624

Multiply both sides by 4

15624a = 62496 ( divide both sides by 15624

a = 4

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.