Answer:

Step-by-step explanation:
Greatest multiplier of 4 that is less than 21 is 5 (4 x 5 = 20)
Put the remaining number as the numerator (21 - 20 = 1)
Answer:
-6/4
Step-by-step explanation:
-13/4+7/4=
=-6/4
Step-by-step explanation:
1.923% (Roughly)
You can get this by dividing 1 by 52 to find the likelihood. <span />
A petri dish is simply a circle; thus, we use the formula of the area of the circle which is <span>πr^2.
Given r = 40 mm
A = </span>π(40)^2 = <span>5026.55 sq. mm
</span>
Population density = bacteria count / area
PD = 2,100 / <span>5026.55
PD = </span><span>0.417782 bacteria / mm sq.
Therefore, the answer is approximately 0.418 </span><span>bacteria per square millimeter.</span>