Indices

[HarvardDreamin]

Q1) If p, s, and t are positive prime numbers, what is the value of p^3s^3t^3?
(1) p^3st=728
(2) t=13

[tmmyc]

1) First, break 728 into its prime factors.

728 = 2 * 2 * 2 * 7 * 13

Then, make it equal to the 'pst' formula.

p^3*s*t = 2*2*2*7*13

Therefore,
p = 2
s*t = 7*13

and
p^3=8
(s*t)^3 = s^3*t^3 = 7^3*13^3

Sufficient, since we can find p^3s^3t^3.


2) t=13 tells us nothing about p ands, therefore this is insufficient.

Answer is A.

[HarvardDreamin]

Many thanks

[cjiang16]

thanks.