function atLeastHalf(array) {

  let res = 0;

  const half = Math.ceil(array.length / 2)

  for (let i = 0; i < Math.pow(2, array.length); i++) {

    if(bitsOn(i) < half) {

      let col = 1

      for(let c = 0; c < array.length; c++) {

        col *= ((i&1<<c) ? array[c] : 1 - array[c])

      }

      res += col

    }

  }

  return 1 - res

  function bitsOn(number) {

    let value = 0

    for(let i = 0; i < 8; i++) {

      value += number&1<<i?1:0

    }

    return value

    }

}

​

console.assert(atLeastHalf([0.1, 0.2, 0.3, 0.4]) == 0.2572)

console.assert(atLeastHalf([0.9, 0.9, 0.9, 0.9, 0.9]) == 0.99144)

​