Question 1145496
Selling "less than 4 properties" means selling either 3, 2, 1, or 0 properties.
<pr>
Probability of selling exactly 3 properties in one week: {{{(0.5)^3 * (0.5)^12 * (15!/(3!*12!))}}} = 0.0139
Probability of selling exactly 2 properties in one week: {{{(0.5)^2 * (0.5)^13 * (15!/(2!*13!))}}} = 0.0032
Probability of selling exactly 1 property in one week: {{{(0.5)^1 * (0.5)^14 * (15!/(1!*14!))}}} = 0.0005
Probability of selling exactly 0 properties in one week: {{{(0.5)^15}}} = 0.00003
<pr>
Probability of selling "less than 4 properties": 0.0139 + 0.0032 + 0.0005 + 0.00003 = 0.01763