An electronic store receives 20 calculators, 7 are defective. Four of the calculators are sent to a high. What's the selections of no defective calculators

4845 selection

Step-by-step explanation:

If the only distinction between calculators is the defects then there are 4 possible selections, namely

0, 1, 2, 3 defective calculators along with good ones for the balance.

If the calculators bear serial numbers, i.e. they are considered distinct, then there are (20,4)=20!/(4!16!)= 4845 selections.

answer:

total cost for tiles and paints is $924.  

step-by-step explanation:

we have been given that a community hall is in the shape of a cuboid. the hall is 40m long 15m high and 3m wide.

the paint will be required for 4 walls and ceiling.

let us find area of walls and ceiling.

therefore, the area of walls and ceiling is 1410 square meters.

given: cost for 10 litre of paint is $10 and 10 litre paint covers 25 square meter. therefore,

therefore, the total painting cost is $564.

tiles will be required for floor. let us find the area of floor.

given: 1m squared floor tiles costs $3. so,

therefore, the total tiles cost is $360.

now let us find combined total cost of tiles and paint.

therefore, the combined total cost of tiles and paint is $924.