1. **Problem statement:** We are given that 7% of teachers are computer science teachers, and the rest are other teachers. Among the other teachers, 94% use MS-Office. Among the computer science teachers, 86% use other office packages, so the rest use MS-Office. We want to find the total percentage of teachers who use MS-Office. 2. **Define variables:** - Let $p_{CS} = 7\% = 0.07$ be the proportion of computer science teachers. - Let $p_{Other} = 1 - p_{CS} = 0.93$ be the proportion of other teachers. - Among other teachers, $p_{MS|Other} = 94\% = 0.94$ use MS-Office. - Among computer science teachers, $p_{OtherOffice|CS} = 86\% = 0.86$ use other office packages, so $p_{MS|CS} = 1 - 0.86 = 0.14$ use MS-Office. 3. **Formula:** Total percentage using MS-Office is the weighted sum: $$ p_{MS} = p_{Other} \times p_{MS|Other} + p_{CS} \times p_{MS|CS} $$ 4. **Calculate:** $$ p_{MS} = 0.93 \times 0.94 + 0.07 \times 0.14 $$ 5. **Intermediate calculation:** $$ 0.93 \times 0.94 = 0.8742 $$ $$ 0.07 \times 0.14 = 0.0098 $$ 6. **Sum:** $$ p_{MS} = 0.8742 + 0.0098 = 0.884 $$ 7. **Convert to percentage and round to one decimal place:** $$ 0.884 \times 100 = 88.4\% $$ **Final answer:** **88.4 % of teachers use MS-Office according to the estimates.**