Solution:Given, total number of pastries sold on Monday and Thursday together = 155
Let the number of pastries sold on Monday be ‘t’.
Then, number of pastries sold on Thursday = (155 - t)
Given, number of pastries sold on Wednesday is 25% less than that sold on Tuesday.
Let the number of pastries sold on Tuesday be 4y.
Number of pastries sold on Wednesday = (3/4) × 4y = 3y
Given, average number of pastries sold on Monday and Tuesday together = 70
According to the question:
=> (t + 4y)/2 = 70
=> t + 4y = 140 ..........(1)
Given, average number of pastries sold on Wednesday and Thursday together = 60
According to the question:
=> (3y + (155 - t))/2 = 60
=> (3y + 155 - t) = 120
=> t + 120 - 3y = 155
=> t - 3y = (155 - 120) = 35 ..........(2)
Subtracting equation (2) from equation (1), we get:
=> 7y = 105
=> y = (105/7) = 15
Putting the value of (y = 15) in equation (1), we get:
=> t + (4 × 15) = 140
=> t + 60 = 140
=> t = (140 - 60) = 80
Hence, number of pastries sold on Monday = t = 80
Number of pastries sold on Tuesday = 4y = (4 × 15) = 60
Number of pastries sold on Wednesday = 3y = (3 × 15) = 45
Number of pastries sold on Thursday = (155 - 80) = 75
Total number of pastries sold on all the five days together = 310
Hence, number of pastries sold on Friday = {310 - (80 + 60 + 45 + 75)} = (310 - 260) = 50
Days | Number of pastries sold
Monday → 80
Tuesday → 60
Wednesday → 45
Thursday → 75
Friday → 50
Number of pastries sold on Wednesday = 45
Number of pastries sold on Friday = 50
Hence, required ratio = 45:50 = 9:10