Question

4. Riya tells a few Mathematics formulae to 3 friends on Sunday. The next day each of them tells
the same formulae to 3 more people. If this continues in the same manner, how many people will
know the formulae told by Riya on next Sunday.
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Answer 1

Answer:

21

Step-by-step explanation:

If Riya tells the formula to 3 people for a week (7 days) 21 people will know the formula.

3 x 7 = 21

Answer 2

on one day, formula known by 3+1 person

this question is a GP

on 7th day, formula known by

${3}^{1} + {3}^{2} + {3}^{3} ........ + {3}^{7} \\ = \frac{ {3}^{8} - 1}{3 - 1} = 3280$