In a classic Conan Doyle story, Sherlock Holmes solves a crime mystery by recognizing that a guard dog didn't bark. Therefore, the dog must have known the perpetrator. Holmes' reasoning goes like this: if the guard dog doesn't know a person, then it barks. The dog didn't bark. Therefore, it knew the person. Which rule of inference is being used here?

a. Addition.
b. Simplification.
c. Conjunction.
d. Modus Ponens.
e. Hypothetical Syllogism.
f. Disjunctive Syllogism.
g. Modus Tollens.
h. Resolution.

G. Modus tollens

Step-by-step explanation:

This question used the inference called modus tollens.

Modus tollens is a a valid form of argument that is of this form below:

If S, then T

if not S, then not T.

S = dog doesn't know perpetrator

Not S = dog knows who the perpetrator is

T = the dog barked

Not T = the dog did not bark.

So if we put this into the statement in bold letters, we would have:

The dog doesn't know perpetrator, so it barked.

And,

The dog didn't bark, so it knows the perpetrator.

4 + 5 7/9= 9 7/9

step-by-step explanation:

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.