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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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The average temperature for Monday, Tuesday, Wednesday, and Thursday was 48°C, and for Tuesday, Wednesday, Thursday, and Friday was 46°C. If the temperature on Monday was 42°C, find the temperature on Friday.
34°C
36°C
38°C
40°C
34°C
Subtract the two sum totals: (Mon+Tue+Wed+Thu) - (Tue+Wed+Thu+Fri) = Mon - Fri = (4 × 48) - (4 × 46) = 192 - 184 = 8. Since Mon = 42, then 42 - Fri = 8, so Fri = 34.
Average temp of (Mon, Tue, Wed, Thu) = 48°C. Average temp of (Tue, Wed, Thu, Fri) = 46°C. Temp of Monday = 42°C.
Average=n∑x
Subtract the two sum totals: (Mon+Tue+Wed+Thu) - (Tue+Wed+Thu+Fri) = Mon - Fri = (4 × 48) - (4 × 46) = 192 - 184 = 8. Since Mon = 42, then 42 - Fri = 8, so Fri = 34.
Students often miscalculate the total sums by forgetting to multiply the average by the number of days (4 days).
Calculate sum for first four days
Given the average for Monday, Tuesday, Wednesday, and Thursday is 48°C, the total sum is 48×4=192°C.
M+T+W+Th=192
Calculate sum for last four days
Given the average for Tuesday, Wednesday, Thursday, and Friday is 46°C, the total sum is 46×4=184°C.
T+W+Th+F=184
Find the difference
Subtract the second sum from the first: (M+T+W+Th)−(T+W+Th+F)=192−184. This leaves M−F=8.
M−F=8
Calculate Friday's temperature
Substitute Monday's temperature (42°C) into the equation: 42−F=8. Solving for F, we get F=42−8=34°C.
F=34°C
A is correct because the difference between the two sums is 8°C, meaning Monday is 8°C warmer than Friday, resulting in 42°C−8°C=34°C.
This concept of overlapping sets is common in both 'Average' problems and 'Age' problems where you compare the sum of groups.
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