If the soloist produces "x" decibels and the 10-person choir produces "y" decibels, combined they will produce "x+y" decibels.
The second choir has 90 additional singers, we base our description on the first choir. If a 10-person choir produces "x+y" decibels, then the 90 person choir produces 10 (x+y) decibels.
Answer:
1050 possible selections
Explanation:
<em>Number of red balls = 7</em>
<em>Number of blue balls = 10</em>
<em>Let blue balls be B and red balls be R</em>
<em>four balls are to be selected. At least three must be blue.</em>
the first combination is 4blue 0red
second combination is 3blue 1red
(10C4*7C0 + 10C3*7C1)
210 *1 +120 *7
210+840
=1050 possibilities