Answer:
Step-by-step explanationjiuijkk8
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Answer:

Step-by-step explanation:
Given
Cost of Textbooks ---- Frequency
$25 up to $35 ----- 2
$35 up to $45 ------- 5
$45 up to $55 ------- 7
$55 up to $65 ------ 20
$65 up to $75 ---- -- 16
Required
Determine the relative class frequency for the $25 up to $35 class
First, we need to get the total frequency


Next, is to write out the frequency of $25 up to $35 class

Divide this frequency by the total frequency; This gives the relative frequency



Hence;
Option D answers the question
First term ,a=4 , common difference =4-7=-3, n =50
sum of first 50terms= (50/2)[2×4+(50-1)(-3)]
=25×[8+49]×-3
=25×57×-3
=25× -171
= -42925
derivation of the formula for the sum of n terms
Progression, S
S=a1+a2+a3+a4+...+an
S=a1+(a1+d)+(a1+2d)+(a1+3d)+...+[a1+(n−1)d] → Equation (1)
S=an+an−1+an−2+an−3+...+a1
S=an+(an−d)+(an−2d)+(an−3d)+...+[an−(n−1)d] → Equation (2)
Add Equations (1) and (2)
2S=(a1+an)+(a1+an)+(a1+an)+(a1+an)+...+(a1+an)
2S=n(a1+an)
S=n/2(a1+an)
Substitute an = a1 + (n - 1)d to the above equation, we have
S=n/2{a1+[a1+(n−1)d]}
S=n/2[2a1+(n−1)d]
Answer: 21,27,28,59,28,100
Step-by-step explanation: first you go on your iPhone and ask Siri ur welcome