Answer:
8 maths tests
Step-by-step explanation:
Given data
We are told that in 1/4 hour that is 0.25hour (15 mins) She grades 1 math test
our aim is to find how many maths test she grade in 3 hours (120min)
Hence
in 15 mins she does 1 grading
in 120 mins she does x
cross multiply
15x= 120
divide both sides by 15
x= 120/15
x= 8 maths test
Hence in 2 hours, she can grade 8 maths tests
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Answer:
18
Step-by-step explanation:
A two-digit number (xy) will have the value 10x+y. The sum of its digits is x+y.
You want ...
10x +y = 2(x +y)
1 ≤ x ≤ 9
0 ≤ y ≤ 9
The equation can be simplified to ...
8x = y
The only single-digit values for x and y that satisfy the requirements are ...
x = 1, y = 8
The two-digit number of interest is 18.
_____
<em>Check</em>
Its sum of digits is 1+8 = 9. 2×9 = 18.
_____
<em>Comment on the relationship in the problem</em>
Many of us learned our multiplication tables for 9s by remembering that the sum of digits of 9n was 9, and that the leading digit of the product was n-1.
Answer:
a. 1,275.49 m²
Step-by-step explanation:
SA = 2πr² + 2πrh
SA = 2π(7)² + 2π(7)(22)
SA = 98π + 308π
SA = 406π
SA ≈ 1,275.49 m²
