Four excavators get rid of two tons of mud in 2,5 hours. How long does it take seven excavators to get rid of five tons of mud?

Three people (Adam, Ben and Charles) smoke three different brands of cigarettes (Petra, Camel, Sparta) and drink different types of alcohol (beer, wine, liquor). We know that:

• Ben drinks liquor.
• The one who drinks wine smokes Sparta.
• Charles smokes Camel.

Which one of the following statements is true?

Three languages are taught at a high school: French, English and German. We know that:

• Every student learns at least one foreign language.
• 90 students learn exactly two languages, each combination of two languages has the same number of students.
• One quarter of all students learn all three languages.
• There are 200 students at the school.
• 135 students learn French.

Choose an incorrect statement:

There are five cups on the table next to each other. Each one has a different colour: pink, yellow, green, blue and red. We know that:

• Pink and yellow ones are not immediately next to each other, pink one is on the left of the yellow one.
• Blue one is to the left of the red one.
• Green one is on the left edge of the row.

In which order can the cups stand?