4000 out of 10000 voting residents are against a new sales tax. Hence, "10000-4000=6000" residents favor the new tax.
Use the hypergeometric distribution with "N=10000, n=15, k=6000,x=0\\ \\text{to}\\ 7,"
"P(x;N, n, k)={\\binom{k}{x}\\binom{N-k}{n-x} \\over \\binom{N}{n}}""P(0;10000, 15, 6000)={\\binom{6000}{0}\\binom{10000-6000}{15-0} \\over \\binom{10000}{15}}=0.00000157"
"P(1;10000, 15, 6000)={\\binom{6000}{1}\\binom{10000-6000}{15-1} \\over \\binom{10000}{15}}=0.00002386"
"P(2;10000, 15, 6000)={\\binom{6000}{2}\\binom{10000-6000}{15-2} \\over \\binom{10000}{15}}=0.00025135"
"P(3;10000, 15, 6000)={\\binom{6000}{3}\\binom{10000-6000}{15-3} \\over \\binom{10000}{15}}=0.00163816"
"P(4;10000, 15, 6000)={\\binom{6000}{4}\\binom{10000-6000}{15-4} \\over \\binom{10000}{15}}=0.00738837"
"P(5;10000, 15, 6000)={\\binom{6000}{5}\\binom{10000-6000}{15-5} \\over \\binom{10000}{15}}=0.02442644"
"P(6;10000, 15, 6000)={\\binom{6000}{6}\\binom{10000-6000}{15-6} \\over \\binom{10000}{15}}=0.06115280"
"P(7;10000, 15, 6000)={\\binom{6000}{7}\\binom{10000-6000}{15-7} \\over \\binom{10000}{15}}=0.11805571"
"P(X\\leq7)\\approx0.00000157+0.00002386+"
"+0.00025135+0.00163816+0.00738837+"
"+0.02442644+0.06115280+0.11805571\\approx"
The probability that at most 7 favor the new tax is "0.212938."
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