3951 is an example of a standard form.
What standard form means is the number is written in numerical form.
More examples: 5269, 95862, 125634, etc.
Answer:
Once.
Step-by-step explanation:
To find when they chirp together, we must find the LCM of the two numbers. The LCM, or least common multiple of 13 and 5 is 65. Therefore, after 65 minutes is the first time they chirp together. Then we can multiply 65 by 2 to see if they chirp a second time. 65x2 is 130, but 8AM-10AM is only 120 minutes, therefore they do not chirp together more than 1 time.
Solution :
The test is distributed normally with mean of 72.8 and the standard deviation of 7.3
Finding numerical limits for the D grade.
D grade : Scores below the top 80% and above the bottom 10%.
Let the bottom limit for D grade be 
and the top limit for D grade be 
.
First find the bottom numerical limit for a D grade is :
..........(1)
From (1)
= 63.45
≈ 64
Now the top numerical limit for D grade :
..........(2)
From (2)
= 66.668
≈ 67
Therefore, the numerical limit for a D grade is 64 to 67.
Multiply denominator (in this case do 6x10)
Multiply the numerator (in this case do 1x1)
So the answer is 1/60
