Question

one fourth of all telephones at the office have built-in speaker phones. 1/2 of the phones with built-in speaker phones have conference call capability. how many phones in the office have both speakernphone and conference call capability?

Answer 1

Let number of telephones in the office be represented by "x"

Number of telephones that have built in speaker phones = 1/4x

Number of telephones that have built in conferencing capability = 1/2 * number of phones with built in speaker facility

Number of telephones that have built in conferencing capability = 1/2*1/4x = 1/8x

Number of telephones that have built in conferencing capability = 1/8x