Answer with explanation:
We have to estimate the sum of
→7.95 + 8.11 + 78.5 + 8.05 + 79.4 + 0.815
When Rounded to nearest tens
7.95 → 8.00
8.11→ 8.00
78.5→79
8.05→8.00
79.4→79.0
0.815→1
So,estimation of the above rational numbers with addition as an operation is done,the result is
→8 + 8 + 80 + 8 + 80 + 0.8 = 184.8, is not correct ,because in the expression it is not clear , the numbers are neither exactly rounded to nearest tens or tenths.
for example ,79.4 when rounded to nearest tens → 79,but in the expression 80 is written,which is not correct.
Similarly,when rounded to nearest tens, 0.815 → 1, but in the expression 0.8 is written,which is confusing.
Similarly,when rounded to nearest tens ,78.5 →79 , but in the expression 80, is written,which is incorrect.
