C

1003170803

Level: 
C
Loudness refers to how loud or soft a sound seems to a listener. The loudness L of sound in decibels, (dB) is determined by the formula L=10log⁡⁡(II0), where I is intensity of the sound waves (in watts per square meter, W/m2) and I0 is fixed and determined intensity of the sound (10−12W/m2) that can barely be perceived. The intensity of the sound produced by the rock band is about 100 times greater than the intensity of the sound emitted by conventional motor vehicles. How much greater (in dB) is loudness of rock band than loudness of motor vehicles?
20
100
10
2

1003170802

Level: 
C
The acidity of a substance is measured by its pH value. In practice, pH is often assumed to be the negative logarithm of the hydrogen ion concentration H+ (i.e. the number of moles of hydrogen ions per liter of solution): pH=−log⁡(H+). If an apple juice has a pH of 3.8 and a grapefruit juice has a pH of 3.6 then the hydrogen ion concentration (mol/l) in the apple juice is how much less than in the grapefruit juice? Round the result to six decimal places.
0.000093
−0.000093
1.584893
0

1103170801

Level: 
C
The acidity of a substance is measured by its pH value. In practice, pH is often assumed to be the negative logarithm of the hydrogen ion concentration H+ (i.e. the number of moles of hydrogen ions per liter of solution): pH=−log⁡(H+). In one of the following pictures is a part of the pH−H+ graph. Choose the picture.

1003164304

Level: 
C
Which of the following situations could arise for suitable functions f and g?
limx→2f(x)=∞ ∧ limx→2g(x)=−∞ ∧ limx→2[f(x)+g(x)]=−∞
limx→2f(x)=13 ∧ limx→2g(x)=0 ∧ limx→2f(x)g(x)=13
limx→2f(x)=−∞ ∧ limx→2g(x)=∞ ∧ limx→2[f(x)−g(x)]=0
limx→2f(x)=∞ ∧ limx→2g(x)=−∞ ∧ limx→2[f(x)⋅g(x)]=∞

1003164303

Level: 
C
Which of the following situations could arise for suitable functions f and g?
limx→5f(x)=0 ∧ limx→5g(x)=∞ ∧ limx→5[f(x)⋅g(x)]=13
limx→5f(x)=1 ∧ limx→5g(x)=∞ ∧ limx→5[f(x)⋅g(x)]=13
limx→5f(x)=∞ ∧ limx→5g(x)=∞ ∧ limx→5[f(x)⋅g(x)]=13
limx→5f(x)=−∞ ∧ limx→5g(x)=∞ ∧ limx→5[f(x)⋅g(x)]=13

1003164302

Level: 
C
Which of the following situations could arise for suitable functions f and g?
limx→2⁡f(x)=∞ ∧ limx→2g(x)=∞ ∧ limx→2[f(x)−g(x)]=∞
limx→2⁡f(x)=1 ∧ limx→2g(x)=∞ ∧ limx→2f(x)g(x)=1
limx→2⁡f(x)=−∞ ∧ limx→2g(x)=1 ∧ limx→2[f(x)+g(x)]=1
limx→2⁡f(x)=−∞ ∧ limx→2g(x)=−∞ ∧ limx→2[f(x)⋅g(x)]=−∞

1003164301

Level: 
C
Which of the following situations could arise for suitable functions f and g?
limx→3f(x)=∞ ∧ limx→3g(x)=∞ ∧ limx→3f(x)g(x)=5
limx→3f(x)=1 ∧ limx→3g(x)=∞ ∧ limx→3f(x)g(x)=5
limx→3f(x)=∞ ∧ limx→3g(x)=1 ∧ limx→3f(x)g(x)=5
limx→3f(x)=0 ∧ limx→3g(x)=∞ ∧ limx→3f(x)g(x)=5

1003197408

Level: 
C
The painter A takes 15 hours to paint a flat. The painter B takes 12 hours to paint the same flat and the painter C takes 10 hours to complete the same task. The painter A starts to paint alone and after 2 hours joins him the painter B. After the next hour the painter C starts to paint with them too. How long will all three painters paint together before completing the work?
2h 52min
3h 8min
3h 24min
4h